A deck saloon and even more this large pilothouse look surprising re. the stability of such a centerboard sailboat, with a ballast usually positioned higher vs. a standard keel boat ?
The hull bustle, a kind of keel embryo perfectly integrated into the hull design, hence the name "integral centerboarder", allows the lead ballast to be lowered, in addition to a density greater than pig iron or steel shot often used on other centerboarders, as well as the engine (which also gives an almost horizontal shaft for better propeller efficiency) and part of the diesel tanks. Moreover, the superstructure of the pilothouse with its waterproof coachroof will allow the sailboat to recover faster in the extreme case of a capsize. The stability curves of the Enduro 54 and STIX calculations (see the boat performances) are comparable to the best keelboats with the bonus and advantage of being able to move the CLR (center of lateral resistance) backwards, when sailing downwind, by raising the centreboard, the boat being like on rails then, in addition to a more gentle motion in rough seas.
Which system is used to lift the centreboard ?
Re. lifting device : A strap plus a double block tackle with a dyneema line going back to a cockpit winch is used to lift the board.
Given the boat program, a simple, reliable and moreover a device which can easily be fixed on board has been favored. The centerboard is moderately ballasted, non only to improve upwind performance, but moreover not to float given its thick Naca profile, and simply go down by gravity. It is possible to navigate safely with the board partially or totally lifted up, due to a relatively small change of the overall boat VCG (vertical position of the center of gravity) and still quite satisfactory stability results.
A rack system with a security pawl allows maneuvering in total serenity. For comfort the largest central cockpit electrical winch is used, however it is good to know this lifting system has been satisfactorily working on several other boats with only manual winches and even in some cases with a heavier ballasted centerboard. Hatches all above the waterline grant access to the lifting device including a possible change of the lifting rope, and even the main strap, without having to haul the boat out. Besides this, a deck window hatch aligned with the centerboard trunk hatches, allows the installation of a hoist to remove the centerboard for important maintenance work. Scantling of the centerboard shaft is generous and the trunk guides are made of Vesconite, a premium durable low friction and stable polymer. The trunk closing device when the centerboard is in the down position for superior hydrodynamics can also be accessed from the trunk hatches.
It is also possible to use a cylinder and an electric hydraulic pump, but without direct connection of the cylinder to the centreboard to avoid heavy loads in the event of an impact or any accidental grounding. A "push-button" system but which can be put in degraded mode towards the basic manual system as a fall-back, in the event of a cylinder malfunction, while remaining afloat and with the means available on board.
Why not using a single rudder aligned and protected by the centerboard ?
First of all, see the FAQ on the high efficiency, but also vulnerability, of twin rudders.
A single rudder must be deep enough to be effective, not really compatible with a low draft boat. On centerboarders, the old solutions developed in the 1980-90s are either an articulated rudder with the drawbacks of poor hydrodynamics and often a permanently submerged cylinder, or the addition of 2 daggerboards aft to compensate for a too short rudder .
A central rudder is certainly protected by the centerboard and skeg on the same longitudinal axis, but not the rear daggerboards which are as exposed as the twin rudders. Moreover a single rudder is not protected laterally e.g. when the current or ice floes push the boat towards rocks (see Fleur Australe damaging her rudder twice, in the Arctic and also in Antarctica). Other well known boats have twisted their rudder entering a coral atoll with an opening or "pass" made difficult by strong current or more prosaically in a river ... In this case there is no second or spare rudder to navigate back to a shelter; and to perform a proper fix the boat has to be hauled out !
A major asset of the Enduro 54 resides in its 2 lifting rudders, which can even be removed afloat with absolutely no risk of a leak into the hull, and even inside the watertight rear peak or lazarette.
Being able to remove a rudder along with its rudder tube at sea with zero flooding risk is a real advantage for a true exploration sailboat.
On fixed twin rudders, despite a sturdy aluminum construction and generous scantlings, plus sometimes resin added as a fuse to the upper part of the rudders so as not to pierce the hull in the event of an impact, it is often the bushes or rudder bearings which are damaged, which can cause a leak or at least make steering very hard. Difficult to change a lower bearing without hauling the boat out of the water.
Given the sizeable hatches in front of the coachroof what is planned against heat in tropical regions with the sun high in the sky ?
The preferred solution is an awning rigged above the front panels and hatches of the coachroof (see above images and examples on other sailboats) which can be, by experience, left on at least up to 40N of wind as is the case with a well designed bimini. This awning protects from the tropical sun without obscuring the view forward.
Other solutions include openwork fabric protections such as Batyline fixed directly to the outside of the portholes with some partial transparency from inside, blinds with wide horizontal slats placed inside the boat or even electrochromic "smart glass" panels with an electrical switch to darken the windows or make them fully transparent again.
Under high latitudes, these large panels and numerous portholes allow to enjoy the beautiful lights, if not for a little (and welcome) heat transmitted by the rays of the sun much lower on the horizon.
Why such large tanks with 2000 liters of diesel heavy to transport ?
The boat's program and specifications require a great deal of autonomy. Unlike true polar ships which can carry 3 times more fuel (often in conjunction with a larger engine), it is true that it is approximately double what we see on sailboats with similar programs.
The idea is to be able to get away from the beaten track and remain enough time on site, so as not to have to shorten a stay "at the end of the world" due to lack of fuel, a frustration far too common on many sailboats.
In high latitudes, the consumption of heaters, a central boiler with radiators in all cabins and an additional stove in the saloon, adds to the consumption of the engine where its use is more frequent than in temperate latitudes (polar anticyclone without wind or difficult passages in the ice).
For electricity, solar panels, wind turbines and possibly a hydrogenerator are used, but it can happen that a prolonged stay at anchor without wind or sunshine requires operating the small backup generator ... In addition, this allows an option to install an even more powerful engine and especially to avoid storing numerous heavy fuel jerrycans on deck, which is bad for stability and makes cleaning the deck more difficult (snow, frost, arctic mud).
Having large diesel tanks, given the great carrying capacity of this hull design it is not to the detriment of performance, part of the diesel located at the low point in the bustle contributing to stability (less ballast required), confers many advantages. Purchase of diesel where it is clean or less expensive and since the tanks will not be the most time completely filled in navigation, possibility of ballasting from one side to the other (during long passages), and even be able to adjust the sailboat trim if necessary, given the number and location of the tanks with rapid transfers thanks to small electric pumps.
Why not adding an inverted bow with a negative stem as seen on some newer boats ?
As much as we could see the interest of a full length chine (power, stability, habitability, constructability in aluminium), it is difficult to see the real benefits of an inverted bow on a cruising sailboat with a relatively substantial displacement, apart from trying to convey a modern look.
For a given hull length the idea is to maximize the waterline length while reducing the weights in the heights at deck level and reduce resistance when going through waves, this is OK on light and fast racing sailboats using their mooring very rarely, or on large motor ships.
However on an exploration sailboat having to accommodate a sizeable anchor, often oversized, it would be necessary to lengthen the bowsprit and pulpit, making it less sturdy or much heavier. No actual gain in performance and numerous drawbacks while cruising e.g. during a mooring bow-first at a quay, making it difficult to go overboard. Hence anything close to a plum bow or vertical stem seems like a good optimization relative to waterline length, bow knuckle position and bowsprit design.
Have you considered an electric or hybrid propulsion ?
It is undoubtedly time to consider new propulsion systems. Together with advances in the automotive industry, interesting developments in boat propulsion are to be expected. Looking at the alternatives available today relative to hybrid diesel electric marine propulsion and assessing pros and cons to suit an exploration sailboat program.
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