Slickest folder ever

You need to make a building jig of the deck plan shape and fit the hull in it. Otherwise the hull will twist

A deck jig also holds the hull at a sensible working height

That's what I do with my beach cat designs, as of course do many others

Richard Woods of Woods Designs

www.sailingcatamarans.com

 

Hey guys - To answer the above questions, the boat points very well -- surprisingly well -- because of the deep V hull. The sail actually pulls closer to the wind than any of my other "conventional" sails. The downside is that it takes more water to float than my other boats.
Re tory ply hulls, I have tried it with both 3mm lauan and 3mm okoume, with the same unfortunate outcome: something breaks before the desired shape is obtained. I built a pre-construction model with balsa, and it took the curves pretty well. But the okoume -- which is suppoed to be famous for its ability to take compound curves -- was also a dud. Is "bendable" plywood different from your usual okoume BS 1088?

- Frank

 

I'm surprised you have problems with 3mm ply. Usually that can be really tortured

My Stealth dinghy has very rounded bow sections, yet folds up nicely even with 4mm ply

www.sailingcatamarans.com/stealth.htm

Richard Woods of Woods Designs

www.sailingcatamarans.com

 

Hi Frank, from my experience and as far as I know it - it is. All layers are running in one direction and the middle layer is very thin which makes the wood flexible. You can bend it up to a radius of 9 cm (3,54 inch). You can get it here in Lauan, Meranti, Okume and so on. I think you can get more in USA. For my taste Okoume is best. Meranti is a bit heavy.

http://www.alibaba.com/showroom/bendable-plywood.html
http://www.qualityplywoodspec.com/cat15.html
http://www.winwood-products.com/eng/timber-products/plywood/flexible-plywood.htm

P.S. Sorry, I do not know whether it is British Standard Specification 1088 (Marine Ply). But I was not able to destroy it with my tests.

 

Richard - I have been an admirer of that design since I discovered it a year ago or so. Really a beautiful hull. Maybe I got a bad batch of 3mm okoume. (I ordered it from Noah's -- which I won't do again. It was made in China and gets very wavy and curly just sitting there untouched.) It's bendy OK, but very easy to split along the center grain. Or maybe I just don't know what the heck I'm doing?
Maybe I'll look into that bendable ply. Or maybe I'll just stick with the very well proven "flat-panel" approach I used on all my other hulls, and just use the lauan 3mm, which is just as light as okoume, much stronger, bends well enough, is locally available, is arguably more attractive, seem impervious to the weather -- and costs 1/5 the price!

Cheers - Frank

 

Diy guy,

I don't know about Chinese Okoume, but if you are doing tortured ply, don't put in the bulkheads when you bend the ply. At the least don't put more than one (which I think is still a mistake, but I haven't tried). Do you have a copy of Gougeons Boat Building? You can get a free copy if not. let me know and I'll provide the link. It will just take a little looking. These guys have built some significant boats and show how they did it.

If you want the boat to take much load with bendable ply you will need to use glass for sure. There is no transverse fiber to the ply so it will be easy to break under load without the glass.

 

Hull and Ama Shapes

DIY Frank,

I was studying your new pictures compared to an earlier one and it puzzled me.

Looking for a comment, your philosophy (if that is not too exalted a term) on the Main and Ama hull shapes.
Earlier you had narrow transomed amas which you changed to very full "planning" shapes. It appears to me that at the sail loads you are using the ama is not submerged much past the chine at the side of the hull. So you don't have much immersion.
Then the older main hull had a full transom which you converted to very narrow, almost canoe shaped. Looks like just enough to mount the rudder easily.

Can you describe what led you to reverse both choices and what you think now that you have seen both extremes? I suppose it is hard for you to observe the current main hull in action and we might have to wait for your new videos to try to understand the benefit.

Last question. My beach cat experience pounded home the lesson that you need to actively control where the sailors weight is or risk capsize. In this boat do you ever feel the need to shift your position fwd or aft? I know you are using less than beach cat sail area so it might not be so critical. How do you feel about it when you are sailing?

 

Great questions. This double-ender in the video (and everything on it) has been purely experimental from the get-go. What have I discovered?
- The pointy stern didn't work too well, so I'm going back to a transom -- though a bit narrower one than on some of my previous boats.
- Shallow V-hulls work better than flattish bottoms, and also ride smoother. But the very deep V on this double ender draws way too much water for our shallow local bays, so it's back to a shallower V hull on the boat I'm now building.
- The deep V tort-ply amas I originally made for my boat and Laura's boat work much better all around than the shallow V planing amas. They ride much smoother, provide significant and useful lateral resistance, and never splash.
- The folding amas have worked perfectly from the start, and will be transferred to the new hull with zero changes. Same for the E-Z-Up mast and sail rig, though I'd like to eventually like to make a 100 sq ft sail to replace the current 90 sq ft one, and annd a few more battens that run full length.
BTW, I went to a messabout last Saturday and easily outsailed all 10 or so of the monohulls in attendance. It's really a great little boat "as is" , but I think it will be much with the new shallow V hull + a leeboard (as on all my other boats.) I'll just transplant the akas, amas, mast, and sail, and it all should be great. I will, of course, put everything un on my web site as soon as the photos, videos, and verdict are in.

 

G'day Frank. Thanks for all this 'FAB INFO' I most always am - hanging-out-there - waiting to see what's up next.

Now if I said - try to 'pin-tail' the last 14" run to the transom of the bottom sides of the 'v' - would that make any sense? Know it works & the gain is many many times the cost in effort & the results when sailing are quite astounding.

Now for battens. Batttens 'can' weigh quite a bit - especially if they are a tad long. Suggest you get in touch with a very large mfgr of 'fishing rods' - get some hollow blanks that are seconds in production. Select the right section/length/stiffness etc (you can make a section of the total lenght of the batten - much stiffer by sliding another - slightly smaller 'rod-blank' up the inside) & there - you have it - you can develop a very light-weight batten that bends how & where you want it to. We reduced the total battens weight from 18 lbs down to 3 lbs - &* then went out & won an 'A' class catamaran world championship, then a 'B' class one to keep it company - on the mantle piece.

Good fortune - with all your projects - Fab 2012 & do keep us informed. Ciao, james

PS. Oh & you could make a FRP panel - that is light, stiff, cost effective & ideal for your building method. Comes off the laminating table fully finished (on both sides) & never needs finishing nor gains any water. Maybe time to think?? jj

 

Those plastic lawn chairs have made more than one sailor on this forum happy.

 

You should try out a bean bag chair sometime!
now if they were only CG approved ......

 

Actually, my boy has a big vinyl fabric "bean bag" chair that is actually filled with Styrofoam pellets (best guess). It does not weigh much at all & I am betting it would be great flotation in a pinch.

Unfortunately, I am pretty sure he would notice any relocation attempt.

 

In a letter, Frank has talked about checking on the ability to go to windward by doing comparison sailing against his wifes boat. This is the only practical method I personally know, but he is unique in my experience to have a captive sailing partner with a similar boat to compare against.

The question to the Gents of the Thread: Does anyone know of realatively cheap instruments or techniques by which you can determine the best angle and speed made to windward? It would be nice to have some factual data to see the effect of Frank's or any of our experimentation.
My previous beach cat experience was that I never really completely understood my own boat because I could not quantify and recognize what minor changes did. My "natural" ability is lacking to the extent that I just try something each time I go out, but obviously never learn enough to really progress.

Any help? I don't need multiple $1000's of equipment off a megayacht!

 

back when I used to do LOTS of windsurfing (back in the day) we'd would have loved to have a gps onboard. (until a crash anyway). When I someday get the chance to start testing "Bad Kitty" that is the piece of gear I'll be using. A little triangle course should tell the tale huh?

 

Wow, lots to respond to! Thank you for so many kind words. I really appreciate your interest. If I knew how, I would start my own blog so we could all meet in a place that feels more like home Alas, I'm such a low-tech guy that I can't even figure out how to use the simplest hull design software. So my boat design "plans" consist of -- at most -- a hull profile. (The other 99% of what I do is on my "mental CAD" program.)
- No, not sure what you mean by "pin-tail" the last 14 near the transom," and I'm not sure how that would enhance performance. But I'd really like to know more.
- Believe it or not, my battens are just "screen bead" - plain, unfinished wood -- and weigh virtually nothing. They are not very strong, but are more than up to the simple stresses of this sail design. And in any case, the sail is purely an experiment. If it lasts a few months, that's long enough! But for future versions, I'd definitely like something FRP.
- I would like to know more about the FRP panels and laminating table approach, if you don't mind.
- I gotta tell you, if you can stand all the sneers and jibes you'll surely get, you simply can't beat a good patio chair for a comfortable, waterproof seat. It's amazing! (This assumes of course that you have foot-pedal steering and don't need -- or want -- to hike out.)
- Bean bag chair? Hmm... Yep, good flotation as well, and ultralight...probably.
- Re cheap instrumentation for determining VMG to windward in a scientifically verifiable way: I could probably do that with the various functions available on my Garmin Colorado. It's an amazing little device, with nice map feature options. But I am not super-concerned with data at the moment, because I get to sail so often (thank the Lord) that I have a solid seat-of-the-pants feel for what my different boats are doing relative to each other, and I always sail in the same waters. On my boat No Commotion, I have had five different sail rigs since I launched it 18 months ago. Crazy? Probably. But this has been extremely helpful in determining how much sail I can really use -- and in educating me to the many benefits of unstayed rigs. (My single 102 sf sail has gotten me to 13 mph.)
- It's great having Laura along in her boat as well. Her boat is actually quicker in light air than No Commotion, but the latter pulls away when the wind picks up -- probably due to a bit more sail and a more "speed friendly" hull. My boat tracks better, hers turns better. In the end, it's all about trade-offs.
- Of course, the double-ended boat in the video that this blog is focused on (I'm naming it "Test Bed 1") is lighter than either of our earlier boats, and goes through the water with amazingly little effort, probably due to the points on both ends. But it appears not to have the speed potential of No Commotion, possibly because it's a non-planing hull. Also, it "hobby-horses" too much in any kind of rough water. No Commotion sails virtually flat under the same conditions.
- The good news is, I'm now building an ultra-light new hull (from what's probably a bad batch of 3mm okoume, given all the ripples and unwanted curves) and it will become "Test Bed 2" for the sail and amas currently in the video. The hull is very much like NoCommotion's medium V hull, but a bit less dihedral (it's about 25 degrees amidships). As always, I will report my findings and post photos / videos as soon as I have something worth telling you about.
Cheers - Frank