Initial Stability of Bolger Peapod

[Brian Kelly]

Does anyone have experience with the Bolger Peapod?

Can you stand up in this boat? Can you raise and lower the sprit rig while afloat?

Can anyone compare the sailing stability to an Optimist Pram or a Bolger Bobcat?

Thanks,
Brian

[dredbob]

Brian,

I don't have first hand experience with one, though it is on my list of boats to build, but I think I can answer you, at least in part. As for the standing up, one of the design requirements that Dynamite Payson gave to PCB was that he be able to stand and row facing forward, pushing on the oars, and indeed, there are pictures of him doing just that. As for raising and lowering the sprit rig, I think this will be able to be done relatively easily, mostly from a sitting position. The sprit and the boom (if used) would be removed first, the upper part of the sail folded down, then roll the sail up starting at the clew rolling toward the mast (not around the mast). Tie the rolled up bundle around to the mast with a couple turns. Then just pop up the mast and bundled sail out of the step and lay it down. Raising it would be the reverse. Get the mast in the step, untie the sail letting it unroll but keep a hold of the peak. Put the upper end of peak sprit in place and set the lower end in the snotter, then set the sprit boom. If the peak sprit is the right length, then you should not have to stand to set the lower end in the snotter, which is the trickiest move of the whole sequence, depending on the wind strength, of course.

As for the sailing stability, obviously the Optimist pram will have more initial, static, stability, but the Bolger Peapod will probably have better dynamic ultimate stability because of the deadrise of the lower strake and the freeboard of the upper strake. The shape (which is really more of a double chined surf dory than a peapod) is very seaworthy for a small boat.
The Bolger Bobcat will have better initial stability because of its beam, but its shorter length and larger sail area will tend to make the sailing, dynamic stability more similar to the Peapod with its longer length and less sail area.

I like the design, it's very pretty and the construction looks to be relatively easy, given the shapeliness of the hull.

Bob

[adampet]

Hopefully Stu Fyfe will chime in here soon. He had a Sweet Pea and lots of experience with it.
Adam

[TR]

All things being equal, which they never are in real life, stability increases with the cube of the increase in beam. Thus if a 3' boat is widened to 6', stability increases by 16 times.

Looking at the Bolger Sweet Pea design the beam is 4'4" but the waterline is considerably narrower, I'll guess 3'0". Beam of the Optimist is 3'9" but the sides are about vertical, so her waterline beam increase over that of the Pea is 3.75/3 = 1.25. 1.25*4 =2.44 And so initially the Opti will be 2.44 times more stabile than the Pea.

The Bobcat's beam is 6', waterline about 5', an increase over the Pea of 1.66, and 4*1.66 = 7.7, and so the Bobcat will be 7.7 times more stabile than the Sweet Pea.

But the above comparison is only good at very small angles (1-5 degrees) of heel because these three boats have different hull forms. Because the Opti has a flat bottomed and vertical sided hull, her stability changes very little as she heels, until the bottom comes out of the water when she quickly capsizes. The flared sides of the Pea and Bobcat mean that their waterline width increases rapidly as they heel, and thus stability increases.

Standing up alone in the bow of a small boat is tricky because (due to trim) your weight sinks the end and lifts the wide part of the boat out of the water. Waterline beam is much reduced and so is stability.

All the best, Tad

[dredbob]

TR,

I think that if you only increase the beam, you'll only get an increase in stability by the square, not the cube. By my understanding, which I'll admit is limited, you only get the cube if you also increase length or depth as well. I'm basing this on Dave Gerr's explanation in his book _The Nature of Boats_.

Bob

[Stu Fyfe]

Adam,
My ill-fated peapod was a Beach Pea designed by Doug Hylan. Carl Sylvester in Eastham has a Sweet Pea pictured below.

[adampet]

Right you are Stu,
must not have had enough coffee when I posted that.
Adam

[Brian Kelly]

Thanks for all the great input. Reading about the numbers, and experiencing them are two different things.

I had read that Payson's requirement was to stand and row, I'd forgotten that. I recently was in a 4' beam whitehall of about 14' and initial stability was so low, I felt like a fish out of water. If you can stand and row Sweet Pea, then I think I'd like it just fine. Not a bad choice for building my first boat.

The Bobcat is very wide, but has a V bottom. So ultimate stability was quite good. However, it seemed to easily heel the first few degrees. I was surprised during one gybe when the mast gained momentum and the boat went from starboard to port heel and felt like it might keep going. But it settlied down. For all I know I wasn't anywhere near putting her over, but I'd rather not learn exactly where that line is

A shorter and lighter spar would cut down on the "overshoot" effect. And with the sprit sail, the spars could be tucked away and the mast left in place with a furled sail when rowing.

[Brian Kelly]

Stu, now I am curious. What ill fate begot your beach pea? (another boat I have looked at seriously. It is the design that can be steered by weight shift if I remember)

Brian

[TR]

dred,

Yes, I should have said that stability increases with the cube of the change in size, rather than just in beam. If one could increase beam without changing anything else, stability would increase by the square. But that’s not possible as weight goes up with surface area, thus depth increases, and in fact these three boats are much different in length. So I think my low angle stability comparison above ends up holding true, even if my explanation makes no sense.

Tad

[Boat Tyro]

As a minimalist and a tyro (been sailing for years, the older I get, the smaller my boats become!) I love the peapod as a rowing vessel. She is light, stays on top and will fly if you've got the energy. Sailing is another story. She doesn't like to sail upwind, so if you like to go sideways, with wide tacks, she'll do. I constructed another, deeper shipping keel,thinking I needed balast and side control, but it was ineffective. I may try a simple leeboard. I even put a mini-jib on without result. I haven't had the brass to try the stand-up routine. (LOL) The lines of the boat are what attracted me, so I really don't have a problem with lack of sailing performance. If I want to sail fast, I'd get a cat. Anybody out there that has a better idea for increasing sailing performance, please chime in. Thanks.

[skaraborgcraft]

By TR...."So I think my low angle stability comparison above ends up holding true, even if my explanation makes no sense."

Sorry Tad, but that tickled me.....no offense. Cheers

[skaraborgcraft]

Stick a dagger or centreboard in it. I built a Michalak skiff, didnt like the leeboard and fitted an offset( in the seat front) deep dagger, goes great.

[JayInOz]

By TR...."So I think my low angle stability comparison above ends up holding true, even if my explanation makes no sense."

Sorry Tad, but that tickled me.....no offense. Cheers

That one had me grinning too Tad

Stu Fyfe what happened to your Beach Pea? I have the plans and am itching to start the build but life keeps getting in the way- a sweet little boat that one. JayInOz