22' rowing shell design

[upchurchmr]

Ken,

One of the photos showing the bow (I think) showed the bow section (frame or mold) you are going to keep in the boat leading back to a full section (about 2 feet back I assume).

If you put a straight edge from the bow to that section 2 feet back, it looks like the edge will not touch - the area 1 foot back is narrower than the straight line of the ruler.

That is a hollow. Possibly it was just an optical illusion, but it looks like you ran the bottom strips to be in contact with the whole board instead of gradually flaring out to the round bottom sections.

Some people say that a hollow will gently split the water and give you less wave making drag.

Some people have a lot more experience than I but I doubt the theory above.

Marc

[kfriedman]

oh, gotcha. One of the things about building a long boat is that it's really hard to take a picture of .

In order to get the 2 strips at the top of the bow stem to set up, I needed to pinch in this area. By tomorrow I should be able to remove the tape and the truer form will appear.

I'm not using staples to hold down the strips and the strips aren't cove and bead, so the best I normally do is a strip a day - over the last week I've been getting 2 strips per side on per day which has been great - until today when I stop doing the sides - from now on it's going to be slower.

[upchurchmr]

I've decided I really like staples. Next boat will be full of holes, no skimping where I thought I could.

Are you using hot glue and tape?

Actually if you have good tight joints and good pressure on the glue joint you can remove clamps/ tape/ etc within about 15 minutes (Titebond 2). Loose or gapping joints take a lot longer and may never really get any strength - I discovered.

I keep trying to come up with a clamp that puts consistent pressure on the glue so I can remove them quickly. No luck yet but a lot of sketches. One of my criteria is it has to be cheap and home make-able.

It appeared that you are starting at the sheer and continuing until you finish at the keel. When you do your next boat (!!!) you might find it easier to fit the keel strips by doing the sheer first, then the keel, then alternate until you finish. The only problem then is to do the final strip (the "football") which has to be tapered / fit on both sides.

Looking forward to more pictures.

Marc

[kfriedman]

When I built my first strip kayak I decided to go staple-less because I didn't really need the boat (at that point I already had 4 sea kayaks) and I figured if I was only going to build one, why not. For that and the second kayak (kids boat and the outer island is out on that picassa link) I used hot melt glue after first gluing the strip down and clamping with a wooden u bracket I made (made lots of these). (the good thing about building the follow on boats is that now I have a use for all of the spring clamps I bought for the first boat :-) ).

This boat I started with hot melt glue for the shear but then switched to periodically put a drop of titebond 2 on the taped station - I like this much better as I don't have to scrap the hot melt off later - and it's faster.

Given work, a strip or two a day is a good day.

I like your idea of starting the shear and the keel at the same time - probably would have made the part I'm at now easier, and if nothing else would have give me some variety in the stripping.

On the other two strip boats I built, that last piece was fun - by that point I was getting good at fitting things into tight, awkward spaces :-)

I find that blue painter tape works fine for holding the strips together while the glue dries - generally I'm putting 3 pieces on between stations and more if it seems to need some persuasion.

I'm now at the point where I've broken out my bungee cords for those spots that need more persuading. I'm also at the point where I'm getting to use just about every clamp I own.

Ken

[sfranklin]

Gentlemen, thanks for your insightful comments - I downloaded the Kayak Foundry and am playing around with different LOAs, bearing in mind that the final design would have to be tweaked somewhat for a shell. It's a great tool for calculating the important stuff such as weight, LWL, etc. without the overkill of delftship.

A mention was made of the Triak - cool boat for offshore recreation. I like the idea of outriggers for stability; used on a shell, they would probably have to move aft to clear the oars' working area.

One major concern for me is stability of a shell. I've got the intuition of my current kayak's initial and secondary stability - rolling to the rim doesn't really bother me. But a 24' x 11.6" shell with the rower's CG way above WL worries me a little. That said, I've spent more time in a kayak than in a shell.

With time, I suppose that stability in a recreational rowing shell is a learned skill. Will probably peruse drop-in rig designs which show position relative to WL. The Carl Douglas Custom 1X box is functional and beautiful - I will come as close as possible to that design.

Hope your boat projects go well this year!

Steve

[upchurchmr]

Steve,

Good luck, the Douglas and Pocock before are stunning boats, you really have something to shoot for.

Have you actually tried a 12" wide shell? You might be able to find someone to give you lessons before you commit to $1-2K and at least a part of a year.

Have fun, looking forward to the build photos.

Marc

[Submarine Tom]

And the sea-trials video.

You do know how to swim right?

-Tom

[upchurchmr]

Steve,

Can't help it, I know you made up your mind, but....
A friend is in hawaii and looking at a Hurricane OC1 which is a ~22' outrigger canoe. www.hurricaneoc.com Take a look and imagine two outriggers, each about 3-3.5' from the side and a sliding seat. Given that the outrigger spread to the oarlocks is ~5' across, I believe you could make the akas and amas compatible with path of the blades. I am at work and could not actually find the width of the Hurricane, but it looks narrower than a typical scull - might be my imagination.

This boat was reputed to be 18#.

Some people might call this the training wheel version. For me it would be a lack of swimming (Ref Submarine Tom's comment).

Happy New Year

Marc

[kfriedman]

Steve,

Glad that you got a copy of Kayak Foundry - it's a pretty nice program - Ross is my hero.

I know what you mean about the stability curve info - I have a very good idea of what a kayak feels like - but I have no idea what it feels like to sit closer to the deck and slide back and forth... what does a "good" stability curve look like?

Not sure if you've come across flotation stabilizers, but the following link gives one example (edon ts515 training scull) and an approach to improving stability: http://www.youtube.com/watch?v=sQlbob8lykA

I'm 4 strips away from finishing the stripping of my hull. Possibly I will have the boat almost ready for glassing after this coming weekend (I had to go back to work and it's pretty cold out in my garage...). Once glassed on the outside I'm going to have some decisions to make about the placement of the rowing box (e.g. with legs extended, should the rower's position be right at the center of buoyancy, center of flotation or some other point slightly forward of these points?). From there I'm going to have to figure out how the platform should be supported and how to brace the rigging area to maximize strength - all while worrying about making the boat exceed my overall displacement goal

Without riggers, my boat is going to come in at less than $500 with wood, epoxy and glass (I have the seat, will make my own fin/foot stretcher).

btw, I found vespoli had some useful info on different parts and was a nice gut check on the basic dimensions I had in mind: http://www.vespoli.com/boats/singles.php

Ken

[sfranklin]

Very insightful comments, gentlemen - the more I learn, the more I question if it is enough! At some point, we must jump in as if we had good sense, then start the project. I'll view these examples you've provided and hopefully come up with the
best possible design.