St Pierre Dory

Discussion in 'Boat Design' started by BlueWaterMD, Sep 3, 2007.

  1. BlueWaterMD
    Joined: Sep 2007
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    BlueWaterMD Junior Member

    Hi everyone,

    I am new to this forum. I have been reading and there seems to be a ton of great info here.

    Anyway, I have been wanting to build a sailboat for some time now. I absolutely love the St Pierre dory (glen-l has plans for a sail version). This would be my first build. I know the boat is big, bit it appears pretty simple as far as boatbuilding goes.

    While they are beautiful boats, I haven't seen the design used too often in modern boats, and have only been able to find a few examples online.

    http://www.nexusmarine.com/st_pierre.html
    http://glen-l.com/designs/hankinson/ultrapierre.html

    I have also found a boat called the SIlver Gull which appears similar, but in a keel boat design.
    http://www.macnaughtongroup.com/silver28.htm

    Are there any major drawbacks to this design? I am not looking for a high persormance boat, but just want a coastal sailor that I can cruise around in.

    Any advice is appreciated.
     
  2. alan white
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    alan white Senior Member

    As with any design, there are drawbacks. However, the St Pierre dory's drawbacks are not drawbacks for every sailor, just those who demand certain levels of performance (speed).
    You can't put a high-aspect rig on the dory (except maybe a full keel version which is no longer a St Pierre dory at all), since the hull isn't ballasted for tall rigs, and the hull form is also rather narrow, meaning it lacks form stability as well. All of this inability to stand up to lateral forces on the rig pays dividends, however, in sea-keeping abilities. The narrow bottom and high pointed ends, coupled with light weight, allow the dory to survive almost any wave and still remain upright. What allows this is exactly the same thing that limits sailing speed.
    Some might also consider the accomodations to be on the smallish side for a 28 footer, but I would disagree, because it's unfair to use length in creating space expectations. Rather, I'd say displacement is a better index for comparing space, and if that's the case, then the St Pierre has a lot of space for a boat with under 3000 lbs displacement.
    To me, it makes more sense to talk about displacement than length when it comes to pros and cons against other boats. The St Pierre was chosen by Captain Blackburn to make single-handed transatlantic voyages in the 1800s, and he had hooks instead of hands, having lost his hands to frostbite in his whaling days.
    Headroom: Expect no more than 4 1/2 ft or so below--- your feet will probably be six inches below the waterline. Anyone wishing to coastal-cruise in a St Pierre should understand that the galley MUST be located around the hatch (or a large forward hatch). That is one place where standing up is a big bonus. Also, a plan for tenting the cockpit over quickly and easily will extend the living area in all but real crummy weather.
    I worked out a design for a St Pierre recently that has two cabins---- the aft, main cabin has Galley aft (3 ft of counter each side and 30" x 30" companionway hatch) and a double berth/settee with central 4 ft table forward. The leg area of the berths goes under the deck ahead, 30" of space aft of the forward cabin (which houses the toilet and lots of storage for sails, etc).
    The aft cabin is a trunk cabin six feet wide, and the forward cabin is a flush-deck type going entirely across the boat. The single mast buries just ahead of the aft cabin, giving a protected area for dealing with halyards between the two cabins (and even a footwell for forward seating).
    I came up with this layout after a lot of sketching. The aft cabin seating area has windows on three sides at eye level- a perfect place to sit and see almost all around. The settee is the most forward area in the cabin, so there's no need to get past it to use the toilet, as is the usual case.
    This also puts the berths central in the boat, and they can be wide and confortable, if not joinable. The table is double-hinged to rest vertically against the forward bulkhead when not wanted in the way.
    But here's the interesting part of this design: There is no centerboard, but a lifting keel 24" wide x 36" deep below the bottom that raises into the space between the two leg areas of the berths. It passes through the deck when up, which allows beaching. The forward location of the lifting keel means the sail area is also more forward than the typical sailing dory. This is simple, however, by adding a bowsprit and cutter rig.
    There is a slot in the short footwell for the keel to raise through, which also makes for a perfect footwell drain. The mast is perfectly positioned to attach the tackle for raising the keel weight of perhaps 500 lbs..
    The keel nicely balances the engine, a diesel under the aft cockpit that has a sail or vee drive.

    Alan
     
  3. BlueWaterMD
    Joined: Sep 2007
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    BlueWaterMD Junior Member

    I really like the idea of a motorsailor. Ideally what I would like to do is construct a boat with a cabin layout similar to the Nexus Marine boat. It would be driven from inside the pilothouse. Mast would be just in front of the pilot house.

    I also like the motor well on the nexux marine design - takes up less space than the glen-l desgn which is right in the middle of the cockpit. The ability to riase the motor for beachings is also a plus. I would make the motor well smaller, as I would be using a 9.9-15 hp outboard, instead of the 60 that was used on their boat. Also, the motor would be fixed (no steering), but still have tilt. I think I would have to go with twin ridders, so the motor could tilt up between them.

    Any thoughts on centerboards vs daggerboards vs leeboards on such a boat?

    I am just brainstorming right now. I still have a lot to work out on the plans.
     
  4. alan white
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    alan white Senior Member

    Centerboards are the traditional way to go, but they definitely rob space within the cabin, and as such, work well only with center cockpit layouts (and very well indeed). Dagger boards, more properly lifting keels, are a good option if designed to break before the slot does. They will usually hit objects squarely, completely stopping the boat, which can be quite shocking compared to hearing the centerboard go bump.
    Leeboards are a great solution, leaving the cabin free of obstructions, but they have to be fiddled with a bit, and can carry no ballast.
    I like the lifting keel best, recognizing its square forward face is vulnerable--- well so are most fin keels, and at least I can raise up mine if I suspect shoals. The lifting keel can be short fore and aft, but deep, and it can be foil-shaped in section. It can raise completely out of the boat if necessary, as the slot passes right through the boat. That makes maintainence a snap compared to the centerboard.
    The St Pierre, alongside chesepeke sharpies, and such boats as Thomas Day's Sea bird Yawl, have all had fin keels appended to their undersides, but there is much disagreement about the value of doing so. Ultimately, seaworthiness and handiness aren't so much a product of ballast down low. It's true you can carry more sail with a deep ballast, but much of the extra sail area is only transporting the extra ballast around anyway. A light and buoyant hull with a low rig has smaller sails and is more yielding to waves, and can ride out some pretty bad weather. Read what Phil Bolger has to say on the subject.
    To get stand-up room in a St Pierre, you will not be able to get the sailplan down low enough to be able to sail efficiently UNLESS your rig is configured to allow sails to miss the pilot house entirely (see Romilly, little sister to Roxanne, lug-rigged yawls with a generous space between the two sails).
    Even then, the added windage of a tall cabin is going to have an adverse effect on sailing performance when going to windward. I would suggest you lower the pilothouse a foot or so and comprimise, unless you intend to motor only.
    Any case, twin rudders aren't necessary or desirable so close together. The rudder can be designed with a relief area for the prop, with some area added on aft of the original trailing edge to compensate. Alternately, the motor can be set up to one side of the transom on a lifting mechanism (I have one of these in parts in my barn--- all stainless, it lifts with a lanyard to a sheet winch ----a full three feet).

    A.
     
  5. BlueWaterMD
    Joined: Sep 2007
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    BlueWaterMD Junior Member

    Thanks for all your advice. It is really helpful, especially as I don't have as much knowledge of yacht design as many others on this site.

    To cut down on height, the pilot house that I was considering would only be designed for sitting headroom. It would have a retractable hatch for standing through if the need arose. Still, it would raise the height of the sails considerably and add for extra windage.
     

  6. alan white
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    alan white Senior Member

    It seems like the 27 ft dory would allow the requisite 5 ft required for sitting headroom--- the boom height seems to come in at around 6 ft above the water every time I draw the boat. To avoid decapitation, it might be wise to dispense with the boom altogether if the sail is sweeping close to the cabin top, or a sprit boom could be used.
    The bigger concern is the view ahead---- at five feet, the cabin ahead must be at least a foot lower in order to be able to see. You need at least 4 ft 6", and preferably 4' 8" in the settee area, for the head, and for any nav station.
    That puts the pilot house roof up at 5' 6" or more. Yet, I think so long as it's not a long pilot house, and the sail is boomless, you still won't raise the sail height.

    A.
     
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