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View Full Version : Geodesic boats - easy?



posmentier
04-19-2013, 09:23 PM
I'm a beginner boatbuilder, having done a fair job building one stitch-and-glue lapstrake open Kayak kit by Eric Schade. I'm thinking of my next project - a geodesic skin-on-frame "Sweet Pea" by Monfort for my granddaughter. It requires steam-banding and heat-shrinking a dacron skin. The gaboat website makes it sound easy and fast.:) But I just read the website http://home.fuse.net/thewizard/, and they make the technique sound VERY complicated.|:( Can an older builder with two left thumbs do a decent job of one of these boats?:confused:

Thanks,

Eric

James McMullen
04-19-2013, 09:50 PM
Skin on frame boats are easy and fast. Don't worry too much about it, you'll be fine!

David G
04-19-2013, 09:56 PM
James is both correct and convincing.

And... before you make your final decision... you might want to peek at the SOF designs of our very own Dave Gentry. I've seen some of his in the flesh, and was impressed:

http://www.gentrycustomboats.com/

capefox
04-19-2013, 10:52 PM
I've always wondered - can you build an SOF and then glass the hull. In other words, the SOF hull serves as a mold for a glass hull.

JimConlin
04-19-2013, 11:06 PM
Why add all that weight, cost and labor?

When you mix two dissimilar materials, one of the materials' properties will be wasted.

htom
04-20-2013, 12:20 AM
I've always wondered - can you build an SOF and then glass the hull. In other words, the SOF hull serves as a mold for a glass hull.

Well, you obviously could, but doing so doesn't make much sense to me. I don't think you'd get a fair hull out of such a process, as well as wasting the time, materials, and money making the frame. You'd be better off using some form of stripper hull.

andykane
04-20-2013, 01:23 AM
I built a boat to his Arrow 14 design. I'd say it definitely took longer than the website would lead you to believe, but it's not hard. I was into it for about 90 hours till it was ready to launch. I think I did a better than average job but you could spend lots longer if you really wanted to clean up all the epoxy squeeze out. You could also save time by not twisting the stringers and just using more epoxy, or not making the floorboards as nicely, and so on and so on.

If I were to do it again I'd probably just lash it. I don't think you really save much weight doing the kevlar/glue thing, and it does take quite a while. Ditto the heat 'n bond... staples are just so easy.

Steaming is pretty time consuming, especially since I could only do 5 or 6 ribs at once with the clamps I have (that alone takes like 30 clamps). I'd expect plywood frames to be easier and faster but not as pleasant as steaming (which I quite enjoyed).

I would try to find some polyester skin rather than the ballistic nylon I used - the polyester heat shrinks, nylon just stretches when it's wet so you have to install it wet with the hope it will dry and be tight... which it is, until it gets wet which seems inevitable to me (what with it being a boat, ya know).

The key is to not waste too much time trying for a perfect shape. The skin and frame just bend and tend to fair themselves into whatever shape they feel like, so don't sweat the little details. I bet that sweet pea would be a great boat for your granddaughter - plenty light to manage easily.

http://ochaye.strangepics.net/temp/arrow_14_01.jpg

http://ochaye.strangepics.net/temp/arrow_14_02.jpg

http://ochaye.strangepics.net/temp/arrow_14_03.jpg

Greg Nolan
04-20-2013, 08:13 AM
There is a pair of pretty good videos showing the construction of the similar Airolite Nimrod canoe:

http://www.youtube.com/watch?v=HBkZWGETPtI
http://www.youtube.com/watch?v=fBxwU-ekvm8

Does not look hard at all.

PaulT
04-20-2013, 08:41 AM
Eric:
I built a Classic 12 from them and it went as advertised, time frame notwithstanding. I used blue foam from a big box store for a steam box... Shrinking the dacron was no big deal..Household iron, walk around it shrinking as needed... It all went according to Platt's instructions. I've read a website where it was made out to seem very difficult. I figure either the folks who put up that story were either trying to tell a funny story or were not able to read and comprehend very simple instructions.
In my case the plans produced a very nice looking and very functional boat that receives compliments frequently. It's stored under a carport year round. I pick it up , walk to the waters edge and plop it in. The boat has been punctured during a storm when a piece of plywood stored outdoors by a neighbor took flight and poked a hole (tear) about two inches long in the skin. White ducktape repair and off I went again. In truth, I feel sure if that piece of ply had hit a thin plywood boat the damage would have been similar... Who knows.

Edit... I think this link will work to my thread.. http://forum.woodenboat.com/showthread.php?87818-Launched-it!&highlight=

PaulT

capefox
04-20-2013, 08:57 AM
After the duct tape how did you make a permanent repair?

andykane
04-20-2013, 01:32 PM
The GA boats can be patched with the same heat 'n bond glue that the skin is attached with. It's basically a tape of the same plastic used in hot melt glue guns with some adhesive on one side to hold it before it melts. You'd just cut a patch, apply the tape, and then iron it into place.

PaulT
04-20-2013, 02:14 PM
Capefox
As Andykane has said, same heat-n-bond, dacron and an iron.. A little bit of clear or color of your choice, and done... Although my duct tape has been there for about a year and is doing fine. I'll repair it, eventually.
PaulT

Idonthaveaboatbutwantto
02-26-2017, 10:43 AM
Is there much in the way of free SOF canoe plans? If so, are there any that have cutouts so I can put them on wood and cut those out?

Breakaway
02-26-2017, 11:01 AM
Hi Idont

You can buy SOF plans for about 60 bucks. You will probably spend $500 to $800 on materials, so in the scheme of things, plans are cheap, and don't really add much to the cost of the build.

Not to mention, you then get the professional advice of the designer, which is exactly what a first-timer needs.

If you do find free plans, still please share your build. I am sure the Forum will help you along the way.

Kevin

Idonthaveaboatbutwantto
02-26-2017, 01:27 PM
Thank you for the info breakaway, I'm thinking if getting plans for the sweetpea and your advice is helpful

tink
02-26-2017, 02:40 PM
Just playing Devils Advocate

why SOF? if your granddaughter is less than ten years old I why not a stitch and glue ply boat. My daughter started boating at 8 and until 11 spent lots of her time totally abusing her and her friends boats. This would be capsizing, righting, jumping in and out, as many people as possible kids on it upturned and paddling etc etc. She had great fun, made great friends gained a lot of water confidence but the boats got some serious abuse. She is now a serious boater and passionate about her sailing and canoeing.

I am sure the SOF people will come and defend SOF but I seriously doubt one would survive my daughter and her friends fun. There are plenty of simple designs that you could even build with you granddaughter.

SNAPMAN
02-26-2017, 02:45 PM
Few comments on above to make building easier and a bit faster:

Use zip ties to hold the ribs in place instead of clamps. Harbor Freight has very inexpensive ones.

Simple steamer can be made from a 4' piece of aluminum downspout and a piece of thin sheet metal bent to fit over a 2 quart pot on the stove. Presoak the ribs before steaming.

Stainless steel staples work great for holding the fabric to the gunwales.

Alan
https://sites.google.com/site/helium12sofsailboat/

tink
02-26-2017, 03:01 PM
Just playing Devils Advocate

why SOF? if your granddaughter is less than ten years old I why not a stitch and glue ply boat. My daughter started boating at 8 and until 11 spent lots of her time totally abusing her and her friends boats. This would be capsizing, righting, jumping in and out, as many people as possible kids on it upturned and paddling etc etc. She had great fun, made great friends gained a lot of water confidence but the boats got some serious abuse. She is now a serious boater and passionate about her sailing and canoeing.

I am sure the SOF people will come and defend SOF but I seriously doubt one would survive my daughter and her friends fun. There are plenty of simple designs that you could even build with you granddaughter.

must say a SOF canoe is on my build bucket list

MN Dave
02-26-2017, 03:07 PM
I've always wondered - can you build an SOF and then glass the hull. In other words, the SOF hull serves as a mold for a glass hull.
Fiberglass and polyester or epoxy is a stiff, brittle material with low impact resistance. While quite strong, a single layer of 6 oz cloth is too thin to be of much use by itself because it will bend and break easily. It can reinforce the wood core of a stripper very nicely where the wood and glass work together. Without the continuous layer of wood as in a stripper to support the glass, you need to build up enough thickness to stiffen the laminate and take advantage of the strength of the brittle material. By the time the glass skin is thick enough, it will be much heavier than a flexible fabric and polyurethane skin, and the framework won't be needed anymore. By the same token, building up many layers of fabric and Pu will make a heavy rubber boat that won't hold its shape without a wooden frame.

The Nylon or Dacron skin with polyurethane resin is a flexible, tough material that can absorb a lot of energy by stretching and deforming the structure.



I would try to find some polyester skin rather than the ballistic nylon I used - the polyester heat shrinks, nylon just stretches when it's wet so you have to install it wet with the hope it will dry and be tight... which it is, until it gets wet which seems inevitable to me (what with it being a boat, ya know).
Fit the Nylon skin on the frame while dry. Stitch one end reasonably well and just baste the other stem end. Then remove the skin from the frame and stitch the basted end about 3 inches short (back from the basted seam). Then wet the skin for a few minutes in cold water before stretching it back over the frame. It should stay tight. Both Dacron and Nylon will work. The folks I work with have used both for a number of years and settled on Nylon. Not a huge difference, but a distinct preference. Other builders have gone the other way. This has worked well: http://shop.skinboats.com/2-part-Urethane-System_c5.htm


The gaboat website makes it sound easy and fast.:) But I just read the website http://home.fuse.net/thewizard/, and they make the technique sound VERY complicated.|:(

Don't be put off by overly complicated directions. It is difficult to completely describe every little detail in a simple process without complicating the heck out of it. You could write a 10 page manual for making a peanut butter and jelly sandwich and still miss something. The complicated directions failed to load, probably because I have a lousy internet provider, so I didn't read them. I expect that they tried and failed to describe a simple process in overly complete detail. Some people need everything laid out in minute detail and some don't. If you can think on your feet and work through a few mistakes, you can follow the simple instructions, working out the details as you go along.

upchurchmr
02-26-2017, 03:14 PM
Another option is the Yost kayaks, and I think he had a canoe.
All free plans.
The only thing he asked was that nobody make a business off his free plans.
Apparently some did anyway, and he shut down his web site.

But you can find an archived website here; http://web.archive.org/web/20120126104803/http://yostwerks.com/
These are "fuselage" style boats, with plywood frames (no steaming) similar to Dave Gentry.
This style is not complicated, but anything takes some learning.

upchurchmr
02-26-2017, 03:18 PM
Capefox,

Bill Hamm over on the Guillemot kayak forum has done just that.
He use to teach a class on the technique.
Post a question and he usually answers fairly quickly.

In spite of all the naysaying, apparently the boats were durable and light.
I haven't made one this way.

http://www.kayakforum.com/cgi-bin/Building/index.cgi/page/1/md/index/#m_215803


I've always wondered - can you build an SOF and then glass the hull. In other words, the SOF hull serves as a mold for a glass hull.

MN Dave
02-26-2017, 03:52 PM
Capefox,

Bill Hamm over on the Guillemot kayak forum has done just that.
He use to teach a class on the technique.
Post a question and he usually answers fairly quickly.

In spite of all the naysaying, apparently the boats were durable and light.
I haven't made one this way.

http://www.kayakforum.com/cgi-bin/Building/index.cgi/page/1/md/index/#m_215803

The link is nice, but it will be difficult to locate the right thread. Could you be more specific?

Since you asked over there, I have had good luck (price, packaging and delivery) with Thayercraft for glass cloth. http://www.ebay.com/sch/thayercraft/m.html?item=112290473254&rt=nc&_trksid=p2047675.l2562

upchurchmr
02-26-2017, 04:17 PM
Dave,

I was just suggesting start a new thread.
There is nothing recent that I remember.

The only forum over there to use is the Building one, which is what I provided.
Very few people use or look at the other options.

Thanks for the Thayercraft link.

Marc

mcdenny
02-26-2017, 04:32 PM
If you get tired of paddling the clear finished dacron is translucent so they make a nice chandelier.
https://uploads.tapatalk-cdn.com/20170226/fb1d4cd8309249b4721754d70537192d.jpg

upchurchmr
02-26-2017, 06:15 PM
Beautiful, but my wife won't let me hang a canoe or kayak in the house.
I have the perfect spot.

seedy
02-26-2017, 08:41 PM
Fantastic Denny. You should be in the light fixture biz.

I was up there the summer Bette was selling off the boats, regret not at least stopping by if not carting a few home.