Advantages

Twelve Advantages of a Watson Expedition Yacht

1. Seakindlyness

Ocean passages in a motor yacht need not be an exercise in human endurance; that time has long gone. Today people are far more conscious of noise, vibration and sea motions and the discomfort they invoke, particularly sea motion. A ship in a sea way is subjected to the following mix of sea motions in descending order of importance as far as comfort is concerned:
Rolling
Pitching
Heaving
Slamming
Yawing
Surging
Swaying

The human body is particularly sensitive to the intensity of the accelerations, and to a lesser extent, the amplitude of these motions. Although none of them can be eliminated every effort should be made in hull design to minimize them. Accommodation layouts should also be planned around locations in the vessel where their intensity is least. What steps do we take during hull design to minimize these features?

Rolling
This is the most objectionable of all motions but fortunately is also one effect that can be cured mechanically by the installation of active fin stabilizers. Roll amplitudes can be reduced by up to 90%; even hull forms that would roll in “wet grass” are saved.

Pitching
Excessive pitching is highly objectionable. Experiments have been made with anti pitching fins placed well forward on the hull. Most notable of these experiments was with Royal Navy Anti-Submarine Corvettes in 1970. While pitching reductions of up to 30% were obtained the forces on the fins were so high (five times that due to rolling) they were soon damaged and further trials abandoned. The aim then must be to dampen this motion by good hull design. Research and model testing have focused on fore ship design where it has been found that ships with deep Vee shaped underwater sections in the bow, as apposed to shallow U shaped sections, lead to amplitude reductions of 25% and acceleration reductions of 30%. The model ships used in the tests had a Draft/Length ratio of 0.175. The most severe pitching was found to occur in wave lengths of 1.25 times the ship length. Extensive research has concluded that deep draft ships with Vee sections forward were better able to dampen motions due to pitching. In our craft we always maintain deep Vee shaped sections in the fore ship for the first 25% of the waterline length.

Heaving
Heave co-exists with pitching and is the bodily vertical rise and fall of the hull in a seaway. The research and model testing for pitching has also shown that the deep Vee shaped bow sections reduce heave by up to 50% in the case of the critical 1.25 L wave length over shallow bow sections. The position of the ships longitudinal centre of gravity also has an influence on the heave motion. In fact we have found by our own experiments that the position of the LCG is critical in this respect.

Slamming
Like heave, slamming co-exists with pitching and is caused by the emergence of the lower bow in head seas. In shallow draft craft this leads to very high bottom pressures on the hull followed by structural vibrations extending the whole length of the vessel. Bulbous bows of the simple cylindrical type fitted close to the waterline are particularly susceptible to slamming. Once again the remedy is a deeply immersed Vee shaped hull form.

Yaw
Yaw is an irregular and persistent change of heading caused by quartering seas acting on the bow or stern and wind gusts acting on the superstructure. Not only is this a disconcerting motion but also hard on the autopilot or helmsman. This motion can only be dampened by heavy deep draft hull forms possessing inherent directional stability and low A/B ratios.

Surge
Surge is the periodic speed reduction on meeting and passing through waves. This action is very pronounced in light displacement vessels and is akin to the random acceleration and deceleration of a car by applying the brakes. Hull forms possessing high displacement/length ratios and fine angles of waterline entry coupled with large diameter propellers are far less prone to this action.

Sway
Sway is an irregular athwart ship motion caused by waves and wind gusts on the beam. The only way to mitigate this action again is large immersed underwater lateral plane area and low A/B ratio. Accommodation Locations It has been found by observation and model experiment that the location that suffers least from the above motions is centered at a point 2/3 of the length of the ship aft of the bow. This means that the aft 2/3 of the ship is the best location and the forward 1/3 the worst. Every endeavor should be made to group the most important accommodations in this location. This includes owners stateroom, guest accommodation, saloon and galley and of course the helm station. In our range of vessels from the W54 up we arrange the owner’s stateroom and guest accommodation in this area separated by the engine room space. The forward 1/3 is reserved for extra bunk or crew accommodation. Summary Our conclusions regarding seakindliness are drawn from many years of observation, practical experience and reference to a large body of published research into sea motions. It is clear that correct hull proportions are essential to produce a sea kindly vessel capable of comfortable trans-ocean voyages. Time and again we see otherwise excellent designs spoilt by compromising these essential hull form elements. Chief among these is the obsession with the so called “Bahamian Draft” which severely restricts the designer’s ability to incorporate sea kindly shapes into his design. This is often compounded by excessive top hamper resulting in very high A/B ratios. To make matters worse we see that many designs are further compromised by poor distribution of the accommodation areas in the hull. Unfortunately we suspect that these failings are a typical result of form following fashion. Designers and builders of Expedition Yachts marketed as ocean capable have a responsibility to ensure their product is fit for purpose, not only in terms of seaworthiness, strength etc but equally important, that it possess a high degree of seakindliness.

2. Appearance

For comment on appearance we will refer to the “bible” of naval architecture; “Basic Naval Architecture” by K.C. Barnaby. Barnaby was a leading designer during the halcyon days of the twenties and thirties, a warship designer during WW2 and one of the naval architects responsible for many of the specialist craft used in the D-Day landings. His following comments are simple, descriptive and summarize our own view. “The general appearance of a ship should be indicative of her main function. If a yacht is intended for ocean cruising, the lines should convey an impression of rugged seaworthiness and not of fragile grace or of rapidity of motion. The reverse is true of an up-river vessel which will obviously never have to face heavy weather and which should always look light and neat. On such a type sturdiness will appear to be clumsiness. The main points that govern appearance are sheer, overhangs, rake and height of masts, size and position of windows, ports and funnels and the amount and arrangement of superstructures. In general, all extremes should be sedulously avoided. Overmuch sheer gives a rocking-horse appearance that puts pitching in mind. Too little is ugly and indicates a tendency to wetness. Too much top hamper suggests a possibly quite non-existent propensity for heavy rolling. Too little suggests a lack of space and of amenities. In the first case, every effort should be made to make the ship look as long as possible by means of generous overhangs and a continuity of the sheer line. In the second case, precisely the reverse is required”. There is a modern tendency to give any vessel straight sheer lines, superstructure lines and where possible deck and hull section lines. This is often referred to as “contemporary” styling and is common in all vessels ranging from super yachts, any size motor yacht to ocean racing sail boats. For a long time it has puzzled us why so many designers have adopted this style when it is blatantly wrong for many of the vessel types being built. Now we believe it is the result of embracing technology, the move from the draughting board to the computer screen. It is almost impossible to originate shape such as a pleasing profile with sweeping shear lines on a computer screen, this is drawing board work. Some designers overcome the shear line problem by adding a foc`sle head which serves to give a higher bow. Still however they lack the ocean going shape which inspires confidence in even the least experienced layman. There are advantages to straight shapes, they are easier to build. Not only the hull and superstructure, but also the interior where cabins and living areas are little more than a box shape. In short these are cheaper to build! In our designs we are conservative in the area of appearances. We believe emphatically in the old adage “if it looks right it is right”. Many are of the opinion that our vessels have a traditional look. It is the shapes that are traditional and as Barnaby points out above, it is dictated by the intended use of the vessel. As you read more of our articles I am sure you find yourself looking at ocean going craft in a different light.

3. Built to Class

A vessel should be built to comply with some recognized standard, especially an ocean capable craft. All our craft are offered with the option of Bureau Veritas Classification, one of the worlds leading Classification Societies. Classification is in effect a “Peer” review of the highest order to internationally accepted standards for ship construction; Lloyds Register, Bureau Veritas, Germanisher Lloyd or American Bureau of Shipping, of the hull, machinery and systems design and their construction and installation. Building to Class imposes a high degree of discipline on the designer, builder and subcontractors throughout the build process. The result is that an owner can be assured that all things pertaining to the classification of his vessel are executed to the highest standard. We are unaware of any other builder of expedition yachts who builds to this regimen as a matter of course.

4. The Case for Steel

Of the three common hull materials we have concluded that for the Expedition Yacht class of vessel steel is the most suitable. It fulfills the most important requirements for this class of ship:
• Very high fatigue resistance
• Immense bending and puncture strength
• Collision, stranding and ice resistant
• Fire proof
• Moderate cost It is the only material acceptable to Lloyds Register and Bureau Veritas for “Ice Class” notation. Aluminum and GRP have poor collision, stranding, ice and fire resistance and in the case of GRP the boats are very difficult and expensive to customize if changes involve the hull or superstructure moldings. Lloyds Register and Bureau Veritas do not publish “Deep Sea” scantling rules for GRP and limit Aluminum to 65metres in length. It is significant that these two materials are not considered suitable by these organizations for ship construction. It is also readily understandable why practically every merchant ship in the world is built in steel. Also of interest is the fact that the oldest yacht on Lloyds Yacht Register is over 80 years and built from steel. GRP has proven to be good material for production built sports fishermen and small cruising yachts. Over the last 35 years many more yachtsmen have been able to enjoy the sea as a result of building in this medium. However the suitability of GRP for the construction of Expedition Yachts intended for unrestricted ocean service is questionable. The great argument against steel is corrosion. We have all seen the fleet of vessels in nearly every port in the world; the cargo ships, hard working tugs and fishing vessels. Common amongst them is the sight of rust streaks and basic paint finishes. Always overlooked is the fact that these vessels are designed and built to comply with exacting standards and surveyed at regular intervals to ensure compliance. The material of choice for commercial operators is steel. The fact is no material is immune from degradation; nature will wear down a granite mountain over time! The first and only line of defense for any material; steel or GRP, are its protective coatings. Both steel plate and GRP need this protection in equal measure. Exposed steel will rust and exposed GRP laminates will silently and invisibly degrade through water absorption. Modern epoxy systems have now been used on steel craft for over 25 years and have proved their durability. The difference in durability of gelcoats on GRP hulls and the epoxy and two part poly-urethane coatings generally used on steel hulls is well documented. There are literally thousands of GRP vessels worldwide that have suffered from “boat pox” and have as a solution an epoxy barrier and polyurethane finish, a similar system to that which we apply to steel craft from new! The challenge with both steel and GRP is in detail design to prevent damage and wear and tear to these coatings. In our designs all areas subject to wear and tear are made of or “shod” with polished or painted stainless steel including the following:
• Beltings
• Cap rails
• Bollards and fairleads
• Hawse and spurling pipes
Our first purpose designed Expedition Yacht “Hamal” has this detailing along with a soundly applied epoxy protection system, launched in 1977 she has never been re-painted except for periodic (every 6-7 years) topcoats for cosmetic reasons. There are no signs of corrosion anywhere!

5. Sea Keeping Ability

In our view this is the most important of the essential characteristics because of its profound bearing on the safety of the ship and crew. We would go so far as to say that some of the designs we see are nothing less than negligent in this respect. Good sea-keeping ability demands the following:
• Lowest Possible A/B Ratio not greater than 2. As an example the Watson 72 has an A/B ratio of 1.6
• High Statical and Dynamic Stability. All vessels in our range meet the highest International Maritime    Organization (I.M.O.) Torremolineas Conference Criteria by a minimum 50% margin in every sailing    condition.
• Must meet the I.M.O. “Severe Wind and Rolling” criteria. (This is described in detail in appendix 1).
• Must possess Directional Stability. (This feature is described in appendix 2).
• Deep draft. To satisfy all the abovementioned criteria demands a Draft/Waterline Length ratio (D/L) of    0.15 which is typical of our range of motor yachts. This high ratio may appear to limit navigation in some    cruising grounds; a study we have made of the worlds cruising grounds and marinas certainly suggests    otherwise and besides, are you really planning on gunk-holing in a high latitude capable yacht?
• High standard of watertight closures; all openings within the 60 degree down flooding angle are fitted    with permanently attached hinged metal deadlights or watertight doors. Skylights are fitted with min. ½    inch toughened glass and hinged metal deadlights.

6. Subdivision and Collision Protection

The hull must have at least three watertight bulkheads:
• A collision bulkhead set a minimum of 5% of the waterline length aft of the stem at waterline. This  bulkhead is watertight to the deck head and pierced by no openings and designed to withstand a sea  pressure of 500lbs per sq ft.
• The engine room enclosed between two watertight bulkheads designed for a water pressure of 200lbs  per sq ft. Any doors located in these bulkheads to have equivalent strength to the bulkhead itself.

7. Structural Strength

All our vessels are designed to comply with leading Classification Societies “Rules and Regulations for Steel Ships of Less than 65 metres” with Navigation Notation “Deep Sea” “Deep Sea” is the highest grading under Classification Rules and is intended for vessels for Unrestricted Ocean Service outside ice zones. If it is proposed to cruise amongst ice the hull can be strengthened in compliance with these rules for “Ice Class”. It is significant that Lloyds Register and Bureau Veritas, along with the other Classification Societies do not consider GRP or Aluminum as suitable materials to comply with this standard of construction. The following table shows the sea pressures the “Deep Sea” Notation requires as a design standard for the Watson 72: Location Sea Pressure Bottom Structure Forward 920 lb/sq. ft Bottom Structure Amidships 720 lb/sq. ft Topsides at Bow 500 lb/sq. ft Topsides Amidships 260 lb/sq. ft Deckhouse Front 500 lb/sq. ft Wheelhouse Front 260 lb/sq. ft Steel holds an unassailable position in its ability to meet these loads.

8. Propulsion Efficiency

Motor yacht design is not wholly an exercise in Static’s (although we do wonder sometimes) because they have to be provided with a means of propulsion. For inshore craft used for short trips and low yearly hours any old thing will do. As long as it has a propeller that propels it at its stated speed the efficiency of the system hardly matters. Deep sea motor yachts are quite a different thing altogether. They are expected to do many more yearly hours and we consider it an obligation on the designer and builder to design the most efficient and reliable propulsion system possible. To achieve an acceptable level of efficiency propeller diameters should be at least 7½% of the waterline length. The W72 for example has a propeller diameter of 60inches, which gives high efficiency as well as good staying power in a seaway due to its large swept area. This is important for example a 50 inch propeller has only 70% of the disc area of a 60 inch propeller.

9. Range and Fuel Capacity

All our vessels have large fuel capacity as an example the W72 has fuel oil capacity of approx. 38 tonnes giving a range of over 7000 NM at cruising speed with a weather allowance and 10% arrival margin. This capacity allows for Trans Pacific voyaging and it is our contention that vessels of this class (above 70ft) should have this ability to allow absolute freedom of movement. It seems illogical to us that ships this size should be restricted to say 3500 NM or less in some cases. The point is the capacity should be available even though on a planned voyage only the fuel required for that voyage need be carried. Even our little W48 has capacity for more than 3000 NM at cruise speed. Quite apart from the independence large capacity allows is the difficulty encountered in refueling in secondary ports where fuel can be of dubious quality and the price high. There is no doubt that in many vessels tank capacity cannot be fitted into their hulls due to restricted draft (that old Bahamian mentality again) or the need to meet accommodation requirements or both. Why not meet all requirements including sea keeping ability?

10. Accommodation Layouts

For our range of vessels 65ft and over we make use of the poop deck and aft wheelhouse style. This design enables us to utilize most of the under deck spaces for accommodation, especially the valuable aft part of the ship. It places the engine room in a location always with full head room and convenient for dry exhaust stack trunking. It also results in a more useable fore deck area enclosed by protective bulwarks and is convenient for berthing. Not only does this arrangement allow a far higher accommodation space ratio in the hull, but it also provides a distinct separation between the owner’s quarters and guest/crew accommodations. We also believe that this results in a more pleasing profile. It is our opinion that a high wooded, full two tier, foc’sle head design needs to be at least 90ft to have pleasing proportions, quite apart from having the correct A/B ratio and complying with any known severe wind and rolling criteria. The immense cubic measurement of our vessels along with construction being steel allows for considerable customization of the interior arrangements to suit an owner’s personal requirement.

11. Systems Design & Installation

In the systems installations in our vessels we comply with the Class Society Rules which in the case of piping systems is designed to:
• Protect the integrity of the longitudinal subdivision of the ship.
• Protect the integrity of the fire zones in the ship.
• Protect the integrity of the water tightness of the hull sea fittings. To this end piping systems in the  engine room must be of metal of fire proof material to a specified standard. Valves on the hull must be of  an approved type and make. All essential services in our vessels are provided with not only two means of  locomotion, but also two independent sources of power, in particular:
• Bilge and fire pumps
• Fuel transfer pumps
• Steering gear apparatus It is our view that for complete  safety the Expedition class of vessel should also have the following:
• At least two sources of high tension power; one diesel Genset and one main engine driven shaft  alternator.
• Have two complete sets of anchors and cable deployed for immediate use.
• Have navigation lights that comply in full with the International Collision Regulations.

12 Back Up; Lifetime Technical Support

We design and build our own vessels. Our design office details every part of the vessel. We know intimately every part and piece of machinery that is installed. No item of equipment is installed that in our experience is not fit for duty. Also in most instances any equipment must comply with the requirements of an independent classification surveyor. Along with our standard 365 day warranty for new craft we offer lifetime technical support for our vessels. We now maintain complete equipment, materials and labour file on every vessel built, along with a complete photo library of construction. If you order a new vessel or buy an existing craft we are always available to answer any questions, assist with parts and equipment procurement/substitution or offer advice. ©2005 T.C. Watson & Sons Ltd, Naval Architects, Whangarei, N.Z All rights reserved.

Appendix 1 “Severe Wind and Rolling Criteria”

This is an examination of the ability of the ship to withstand the combined effects of high winds and seas and is mandatory in all ships classed “Deep Sea” with somewhat reduced requirements for vessels under 24 metres in length and coastal waters. It is a three stage application of wind pressure and rolling acting perpendicular to the beam of the ship in the following sequence:
• The ship is subjected to a wind of 54 knots with a maximum permissible angle of heel of 16 degrees or  less depending on the minimum freeboard and beam of the ship
• The ship is then subjected to a roll to windward due to wave action to a specified angle of heel.
• The ship is then subjected to a wind gust of 61 knots.
The ship must have a specified reserve of dynamic stability to resist the above forces. The action of stabilizers cannot to be taken into account. Ships with large windage area, low draft and low beam to draft ratios are particularly sensitive to these dynamics and many we see have doubtful ability to meet them. Ordinary sail boats with ballast keels are innately suitable because of their ability to reduce their windage area at will. This perhaps explains their remarkable safety record. Designers of commercial craft are all familiar with this requirement because in many craft it is a statutory regulation and is always considered in the early design stages. Unfortunately in pleasure craft any stability considerations at all seem to be neglected. ©2005 T.C. Watson & Sons Ltd, Naval Architects, Whangarei, N.Z All rights reserved.

Appendix 2 “Directional Stability”

Along with the optimum coefficients of Form, A/B ratio, Intact Stability and Severe Wind & Rolling criteria the Directional Stability of a vessel built for ocean passages should be a fundamental property of the hull form and considered early in the design. Any designer worth his salt will ensure that all these Hydrostatic and Hydrodynamic properties take precedence over all other elements of hull design. Only in inshore and coastal boats should any of these be compromised. Of all the important design elements this is the one that we consider to be of utmost importance. Of the vessels reported missing without trace each year it is our view that many are more likely to have broached and been overwhelmed than any other possible reason. We don’t buy into the “collision with a semi-submersed” or “neutrally buoyed container” argument; it simply doesn’t stand up to any logical examination. Directional stability is normally defined as “controls fixed directional stability” which means with rudder and any other control surfaces fixed amidships and in the absence of any disturbing forces of wind or sea the vessel, when underway, will maintain a fixed heading. It has to be said that in very few of the Expedition Yacht designs currently offered have the designers considered this property. Directional instability manifests itself in the inability to leave the wheel unattended for even a few seconds without the vessel altering course. This occurs even in calm conditions and in a seaway continuous changes of course have to be coped with by the helmsman. Under normal conditions the argument is that autopilots cope and this is true, albeit with considerable wear and tear on steering gear. Where instability becomes dangerous is running in a heavy following sea, particularly at night, where the autopilot and often the helmsman cannot cope with a tendency to broach to. Directional stability can only be ensured by a proper distribution of the underwater lateral plane about the longitudinal centre of gravity of the ship. To have any degree of stability the longitudinal centre of gravity (L.C.G.) of the ship must be ahead of the longitudinal centroid of the lateral plane (C.L.P). The nearest analogy to this is the feathered arrow. Try firing an arrow without feathers and weighted point. Alternatively a surf board without a fin or used back to front would be un-manageable. Achieving a degree of directional stability is difficult, usually for two reasons; the optimum L.C.G is already aft of amidships and the restricted draft designers are often working to. The only way is to have considerable rake of keel, deeper aft than forward, even if this conflicts with draft considerations. We have found that the amount of separation between the C.L.P and L.C.G is critical to achieving satisfactory directional stability. Time and again we have seen this in our designs and other vessels we have observed. The best is the report back we had from the skipper of one of our Expedition Yacht designs where he found he could leave the helm unattended in reasonably heavy conditions for up to ten minutes at a time. After the research we have done and personal experiences we have in over 50,000 miles of voyaging, there is no doubt in our view that good directional stability is an absolute requirement. The tendency to broach is a serious risk that needs to be eliminated. It goes without saying that vessels with constant draft forward and aft could not possess any satisfactory degree of Directional Stability. An abundance of research has been compiled over the years on this very subject. Our interest in all things of design importance has turned up many case studies of poor directional stability; the following are three stand out examples quoted from The Royal Institution of Naval Architects “Quarterly transactions”, April 1962. Broaching of a Battleship….. Considering (now) the larger power-driven vessels, one author well remembers his first experience of broaching in an old battleship, H.M.S. St. Vincent, during the First World War in a very heavy gale off the Norwegian Coast, in November 1917. “For some hours we had been running before an increasing gale force wind and sea, so when it became necessary at the extremity of our patrol line to turn through 180 deg. on to the reciprocal course the quartermaster probably applied to much helm under the prevailing conditions. The result was a violent and uncontrolled yaw or “broach” into the trough of the sea, while at the same time the ship maintained an outward heel during the rapid turn due to the centrifugal effect of the high CG which is above the waterline, assisted by the location of the ship on the descending wave slope, which, as the ship approaches 90 deg. becomes a slope tending to produce an outward heel”. “Suddenly there was a crash overhead as the wave broke aboard and crossed the ship, causing much flooding below”. “Most of the ships company were asleep in their hammocks so that on being awakened by the crash and finding their ship heeled and staying over they thought their ship had been torpedoed”. An Extraordinary Roll….. There is a case quoted in the Naval Review, extracted from the journal of the US Naval Institute, of a Portuguese destroyer which had gone to rescue the survivors from an American merchant ship sunk by enemy action in the vicinity of the Azores in 1943. After effecting the rescue the Captain found himself about 135 miles from a port in which he could find shelter. He was informed of a forecast of increasingly strong winds up to and beyond gale force, so that he decided to run for port down wind in the hope of entering harbour before darkness. The course was 73 deg. to Ponta Delgarda and the wind backing to the south westerly, so the wind was on the starboard quarter. At first he maintained 18 knots in an increasing following sea. From then on he increased to 20 knots, though steering was very difficult. Then he increased to 22 knots when the ship began to labour to a substantial extent. In the words of the Captain steering became trickier every minute. He therefore decided to try to “get away from the seas” by increasing speed to 24 knots. For a short time matters were improved and the ship seemed to be gaining on the waves. However as the fury of the gale increased the speed and length of the waves increased and the situation grew worse. The ship began to yaw heavily more than 40 deg. and gave the impression of a surf board. They now ordered speed of 26 knots, again with the idea of gaining on the waves, but it did little to improve matters. Eventually as matters became even worse with the increasing fury of the gale the Captain decided to reduce speed drastically but he was not in time: “Suddenly the ship was taken by a great wave and began to such a yaw to starboard that not the whole force of the helm could stop her. She healed slowly over to port more and more….I gave the order stop port engine and finally stop both engines as matters did not improve and we were practically lying down on the bridge with our feet braced against the bulkheads”. “The ship continued slowly but surely to heel further to port. We remained thus for a few awful moments until, at first slowly and then more quickly, the ship righted herself again. It was [found] after that the engine room gauge had registered the terrific roll of over 67 deg. Two First-hand Accounts of “Broaching” from a Yachtsman who is also a Naval Architect ….. verbatim account of broaching given by Howard Chappelle, naval architect, who is curator of the Division of Transport at the Smithsonian Institute in Washington DC. “Broaching, or a tendency to broach is probably more common place in power boats than we realize. I have had only two experiences in person, both mild but startling. In 1926 another fellow and I were running into Ceasars Creek, an inlet between the sea and lower Biscayne Bay, Florida. We had an old 26ft keel sloop, a former sponger, drawing 4ft 3in. aft, and 2ft 6in. forward, jib headed mainsail with a rather long boom. The wind had been a fresh gale from the east, south east for two days and was moderating. There was a sea about 41/2 -5ft high I should guess. We started in, main with one reef in it. For the first mile we had no trouble. I observed as we approached the narrow part of the inlet that the seas were noticeably closer, crest to crest, than before. Suddenly we seemed to over-run a sea, the bow dropped into the trough and then buried. She ran into the sea ahead and suddenly I could not steer her; she turned sharply to port and the following sea over-ran her on the port broadside. She then knocked down but did not capsize. We had about two feet of water in the hold, however. Before the second sea hit her she fell of a little and I was able to get her back before the wind. The whole thing happened very fast and as my mate had cut the mainsail halyard we retained control long enough to get through the inlet”. “The second case was less violent – I was in a 30ft power cruiser at Ipswich, Massachusetts in the fall of 1938. We were running before a rolling sea into Ipswich Bay, to enter the river there. Just as we passed over a roller it broke rather heavily, and the stern seemed to rise very suddenly. The bow must have buried but I could not see as she was raised deck forward. She took a marked heel and sheer, and ran off about 40 deg. to her course, against her rudder”. “I do not recall whether or not we had overrun a sea but she suddenly went out of control to a marked degree. I revved the engine and she came under control again. I did not consider the sea dangerous. The boat had almost no drag to the keel, a long and very sharp entrance and a broad transom. When the stern lifted the boat felt as though she had lost stability. This boat had been built from a half model. I inspected the model later and it was much like a Nova Scotia Cape Island launch, the bearings being all aft. The Cape Islanders have been reported to have been lost by broaching in severe conditions in this manner and for this reason I believe drag to the keel is a “must” in fishing launches. We cannot over emphasize the importance of good directional stability in any vessel, let alone an ocean going motor yacht. ©2005 T.C. Watson & Sons Ltd, Naval Architects, Whangarei, N.Z All rights reserved.

Last Updated (Monday, 19 July 2010 01:34)