Pointy Rear Ends

[JeffM]

Leafing through a couple of Dynamite Payson books the other night I noticed how many of his and Bolger's older "instant boat" designs -- small boats, these -- are double enders. I am trying to figure out why. I seem to recall learning long ago that a boat with a pointy back end handles better in following seas. On the other hand, Graham comments someplace that because such a stern lacks much buoyancy it's easier for a following sea to flood your cockpit. Considering then that a pointy stern 1. reduces buoyancy,

2. reduces useful space,

3. forces the crew forward (owing to both 1 and 2), and

4. reduces lift that might otherwise promote planing,

why would anyone design a double ender in the first place?

[Frank Hagan]

Is it easier to build a boat pointy on both ends in stitch and glue techniques? I wonder if the goal of having no frames or stringers led them to abandon a wider stern on the first designs that were proving the method?

Pure speculation on my part ... they probably just like the looks of the double enders.

[Charlie Jones]

Remember that often in his Instant designs, Bolger tries to get the "most bang for the buck" That is, the biggest boat from the least amount of material.

That could be a part of the reason. Besides, a double ended boat would be simpler to build. Transoms add compilcations in addition to materials.

[PAR]

Double enders can plane, they also can part a boarding following sea, before it gets on your poop. There doesn't seem to be any real tests in regard to this, but cruisers have been touting it for many generations. I have seen this effect first hand, though must question if the waves would have broken anyway, in spite of the pointy butt. I have also seen waves cut in half by the stern of a double ender skidding down it's face, in heavy seas.

They are more difficult to design and a lot will round up hard when on the wind (if not properly designed), because the buttocks have a quick up turn aft. To make a successful double ender, the run has to be especially sweet, with care taken that the buttocks don't turn up hard. This is easier if there is a fair amount of overhang and the butt is drawn out some what. A bad mistake is to try and make the stern sections full and tuck this all in against a stern post in a short distance. It makes a pretty boat, but it will sail to weather like crap, if it can even keep her nose into the wind. A narrow double ender is easier to pull off as a designer, then a plump one. It is the plump double enders that have the most difficulty getting a sweet run to her buttocks, especially if she is full on both ends (am I the only one this is making horny). A full stern and fine bow can drive the boat into seas and cause yawing in some conditions, so there's a lot to balance in the design process. The stern treatment is an element, that has it's own contentions, regardless if it's pointy or not.

Planking a double ender can be a joy, or a headache, depending on how quick the aft planks turn to the stern post. These designs certainly look the best to most folks eyes, but there are sacrifices (like everything in yacht design) to carry a pointy ended boat. As has been noted the stern is cramped, can be wet in some conditions and is just as difficult to work a flogging sail as is the narrow confines of the fore deck. If the hull is designed with a full deck line and "U" shaped sections are employed, you can get flat(ish) buttocks, more room below decks and better bearing area.

I've designed several double enders ("Lass" in the gallery is one), having learned the hard way about keeping the aft sectional shapes proper. My first attempt squatted badly, had little bearing to fight the press in her sails and was a monster to sail into the wind. She also had a pretty full entry which didn't help things and other design issues that become part of the learning process.

I consider Istalena (the Cleat) by L. Francis Herreshoff one of the finest examples of double ender. She was faster then her contemporaries and reasonably dry for what she was. Her ends were drawn out and fine, but the stern was full to the aft end of the LWL, so she had bearing. I think the Tahiti ketches the worst of them, with very full bow and stern, short over hangs and carry so much "burden" they need a half a gale to get along to hull speed. I know I just insulted a bunch of Tahiti ketch lovers and I'm sorry. They do make great liveaboards and good passagemakers (if you're not in a hurry) and many have great treks aboard this design.

[Tom Lathrop]

PAR said just about all of it. Yes, a double ender can plane but, given an identical waterline length, they won't plane nearly as well.

Calkin Bartenders can plane but need horizontal wings under the stern to fool the water into thinking it's a transom ended boat. The ones without these wings squat a lot when trying to plane. Most of the Pangas I see in Mexico also sport these planing wings.

I supect the reason for most of the love of double enders is just that some people like them for appearance. Some like them because they have read that they "part following waves" although very few ever go into such conditions.

Personally, I like the look of a well designed transom better. Except for the wave parting thing, which may or may not hold water :roll:, almost everything else is in favor of the transom stern. It is easier to build strength into a double ender as there is much less exposure to racking forces. Notice how many double enders there are in the round the world races.

[JeffM]

Thanks, all! This is very informative. I'm feeling the temptation to build a Bolger Teal--12ft double-ended single-leeboarder. Its pretty much a one-person boat, but an easy, fast build. I want to see how a boat very different from mine handles. When I'm finished messing with it, I'm betting I can pass it down to one of the boys...

[Tom Lathrop]

Jeff,

You built a Core Sound and now you are thinking about building a Teal? :roll:

I think that is borderline blasphemy.

Graham and I built a Teal in a Sikaflex Challenge contest some years ago. Neither of us could tolerate it and finally gave it away for a charity auction. There are a lot better boats out there. Make that much, much better. Try a Spindrift 10. A bit more work but worth every hour.

[JeffM]

Tom, what did you dislike about the Teal? (You weren't both trying to fit in it at once, I hope?) Actually, my next serious boats will be Birders. But I'm the explorer type, and "instant boats" look like a fairly low-cost way to explore options.

[Tom Lathrop]

Ok Jeff, My prejudices are showing. I don't care for flat bottom boats except in a few special circumstances. External chines just look like you could not do it the right way. The pointy stern on such a small boat robs too much volume from such a small boat. Wanders too much when rowing unless a keel is added.

I just really meant to point out that I think the Spindrift is a much better boat to put effort into especially for one who has experienced a good boat. Build one and let the kids have fun with it if you like.