Small sailboat Design - advice requested

Things are picking up again with me and mine. The hull is being painted and varnished prior to launching as a rowboat. A few more coats to go then I'll post some more pics. Looking good!

The comments on use of screws has set me thinking. Looking at stress in the vertical direction only, using chine logs instead of epoxy and tape introduces a joint between a stiff member (chine log attached to sheer plank) and a flexible member (bottom plank). A load applied to the bottom plank then results in a peeling force applied to the joint, potentially causing veneer failure. A similar stress appears in the sheer plank but is dissipated longitudinally along the chine log because of the greater curvature of the sheer plank. With the taped joint the stress is dissipated because of the flexibility of the joint which equals or exceeds the flexibility of the sheer and bottom planks.

The chine log joint can therefore be improved by tapering the edges of the chine log. This is something I have been trying out, but for weight reduction rather than strength; see picture in post #54 on gluing triangular battens. I need to do some tests on this: theoretically the chine log should have a quarter-circular section machined from it, not easy to do or glue afterwards, but it could be routed in after gluing. The screws achieve a similar result however, and much easier.

 

As I was finishing the hull I realised I do know much about rigging sailboat. The mast will be free-standing and I have information on the snotter for the sprit. I will not bother (initially) with a haliard/top haul (?) as the first sail will be small enough to put onto the mast before fitting the mast.

However, I imagine that I will need a place to tie-off the sheet at the stern, or is it appropriate on such a small boat to just hold the sheet? I don't think the sheet will need any blocks, I can't see a sail on a 10 ft boat generating enough thrust to justify the added complexity.

I was thinking a horn cleat or jamb cleat on each sheer just ahead of the transom would be convenient to have and allow me to concentrate on the tiller.

 

A simple whip tackle is what you want Terry. A single block mounted on the boom and two cleats, preferably quick release, like a cam or jamb style. Each end will fall to the rail (or transom) where it's cleated.

In use, this doubled ended sheeting arrangement is handy. You'll have one end in your hand most of the time, which depends on the tack you're on at that time. This offers a 2:1 leverage on the sail, so you don't wear out holding the sheet. In use to tack; you'll bring the bow up into the wind, cleat the sheet as you switch sides, then grab the new windward sheet during the crossover.

You could get fancy with a swivel block and cam cleat on the stern (see attached), but on a small boat like Dace, I'm not sure it's worth it. Shown is a home made setup, an 1/8" plate of T-6 aluminum, bent as needed. I used a wooden "riser" to lift up the cam cleat to a better location after trials. An eye strap holds the block to the plate, with a genoa car spring between to make it stand up. A disk of HDPE permits it to rotate, friction free. This is through bolted to a piece of angle stock, which holds the whole assembly to the transom.

 

Sheeting for a rig as small as yours can be quite straight forward.

A line can come straight down from the end of the sprit boom to a pully at the transom, near the rudder.

A jamb cleat can then be put on the end of the tiller to hold the sheet temporarily.

The pully could be put on the top of the rudder itself, if you like, but the rudder will then need some kind of hold down device to keep the sheet tension (pulling mostly up, when sheeted in) from pulling the rudder out of its gudeons.

 

Thanks for the inputs guys.

I put the boat in my pool today so I could evaluate the rowing position. It is fine; I can probably raise the seat a little, it is only 8" (20 cm) presently. The oars clear my knees on the recovery stroke, especially if I brace my knees against the bouyancy tank - which is natural for a kayaker.

It may be difficult to keep a straight line and will probably benefit from a small skeg, as Par noted, for rowing.

It feels stable enough to stand up, although it is so light it is like standing on a skateboard; but I will get used to that. Another good case for water ballast perhaps? I will be able to ship the rudder and the mast while on the water, and with me on the side seat it still has both chines in the water. It feels very secrure, more than I expected from this tiny boat.

Unfortunately it looks like it will not get a proper launch this year as there is a problem with the paint. My local hardware store messed up twice. I selected a can of outdoor base paint for tinting, there are 2 types and I got the wrong one so the guy changed it. After I put the first coat on I realised the fool had given me indoor paint! I had it changed to outdoor paint and applied another coat. That was 4 days ago and the damned stuff is still soft and rubbiing of on my clothes and hands. Obviously a bad batch, so I will have to scrape ands sand down to the primer and start over. Next time I will go somewhere else for the paint!

 

Damn I really wanted to see this one in the water!!

How about to place a tin of paint above his door before closing time. Then it will be only him to pass the door to go home.

Nice to hear that the projekt seems to be good!
My little projekt regarding sails in disc is now ready and now I have decided to put ordinary sails and maybe take a little cooling fan engine from a car and make a motor sailer. Must be one of the smallest of its kind.

Hve a nice day, and good luck with the boat Ancient.

 

She should be a fairly stable platform Terry. Of course you'll want to be aware of your movements, but you'll get use to her motion (which will be pretty quick). How much chine was immersed?

 

Terry:

I've been going through paint issues as well. You can read about my adventures on the blog I told you about. Home Depot in Barrie is probably worth a trip - the CIL Alykd exterior paint is what I'm using now with good results. Hard, sands well and the semi-gloss finish is nice. It works quite well with roll & tip technique. There's pictures of progress on the blog.

--
Bill

 

When the boat was in the pool, according to my wife the stem foot and transom bottom were both clear of the water, so she is probably floating close to her design marks. Mo pics yet, although my wife can handle a film camera fine she can't work the digital one with its LED screen, for some reason.

I'll be able to estimate better when I can see a picture. I plan to launch in the local pond Wednesday, weather permitting, and will have a camera-savvy buddy ashore

I have made at least a start on the sailing rig. The hull is still is not fully finished, I want to rub down the varnish and paint with wet and dry and apply another coat to get a better finish. She is getting some scuff marks, when I know where the abrasion areas are I will add some oak strips to take the worst of the punishment she will get in use; they will go on after the finish coat. Despite not being in her Sunday best yet, she is getting compliments already.

 

Nice to hear that the projekt proceeds!
As far as I could see she is looking very nice.

greetings!
Jan Eliasson

 

Yeah, launch is still set for tomorrow (play jaws theme). I am working on the daggerboard and rudder.

(Added Wednesday: of course that was posted on Tuesday based on the weather forecast, which has changed to rain forever, so I hope nobody's holding their breath!)

 

Damn it . . .

 

Pfhui! *sound from Jan Eliasson takin in some new air before he fades out.

 

Monday is next dry day forecast and maybe launch day but the forecasting record isn't very good. In the meantime, the rudder and tiller are ready for finishing. I glued up the blank from the daggerboard, waiting for a buddy to plane it down to thickness. Still wondering how to tackle the mast; have been patiently drying off some fairly decent spruce for weeks.

 

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Terry, you've got to cut this out the suspense is killing me! You've built it well,you've got a great designer -it's going to be a blast! Good Luck! I'll get with my cousin about the weather....