new low cost design competion

Garden row covers are made from a polypropylene fabric. Polypropylene is mechanically tough and highly resistant to fatigue and abrasion. It can be bonded with epoxy. It is vulnerable to UV but so is the epoxy so both should have protection. It may be more environmentally compatible than glass, I don't have data.

My major concern with using the garden row variety is the suitability of the fabric, i.e., weave and thread characteristics, for the application. I would worry about any surface treatment it may have had to provide UV protection, which may have a negative impact on the bond provided by the epoxy.

I don’t think the use of polypropylene fabric for boats should be adopted without investigating its properties and characteristics, and careful testing, but neither do I think it should be rejected out of hand.

Personally I wouldn't use garden row cover material for a boat, any more than I would use glass fiber window screen.

 

Thanks,lampy for the tip

I have a 15 1/2 ft day sailer I built for 300 dollars (not counting mast,sails,and foils which I salvaged from a 30 yr old coronado 15) which I intend to sand down and repaint next yr.Think Ill give the garden row sheathing a try.

Ed

 

some tips

Hi Saw, some tips to help you out. GRC comes in weights from 1/16 oz. up to 3 oz. and I just found out yesterday while looking up prices that is comes in heavier weights for construction of culverts and other places where industry is trying to use recycled material to cut cost. I recommend the ½ oz for your use. The garden verity is smooth on one side and rough on the other. The rough side makes good non-skid, it’s being used for that purpose in the construction of some yachts. Buy it on a roll and keep it on the roll till you use it, because once it gets wrinkles they are hard to get out. It swells a bit when you fill it out so you don’t have to worry about the shrinkage bubbles you get from fibreglass. (that would only be a big issue on the inside anyway) I find a squeegee works better for me but if you like rollers give it a try. Other than that it goes on just like fibre glass, with out the itching.

Dennis

 

The main reason that polyester resin systems are heavy and weak is that the resin doesn't match the fiber's modulus of elongation. Long before the fiber's breaking point the resin has failed, so you have to pile on the resin and fabric, just to have a suitable material.

This is the precise reason polypropylene shouldn't be used as the reinforcement in a thermoset plastic matrix. Used with epoxy the disparity is even more dramatic (compared to polyester or vinylester) . Couple this with the physical nature of polypropylene (it floats in the resin, the fibers will saw through each other, fiber crushing in the weave when tensioned, etc.) and it's clear why it's a poor reinforcement choice.

If use as a sheathing it'll be resin rich, which is the most expensive component of the mixture, the reinforcement will be on top of the resin and it will offer a slight abrasion resistance improvement over straight resin, though anything added to the resin will do this. A better choice would be polyester or polyurethane.

Okay, name the manufacture(s) that is doing this. It's likely that I or someone here knows people, managers, foremen in these shops, we can give them a call and find out the real story.

 

put your money where your mouth is

No my family name isn’t Swain. Considering the positive influence Brent has had on the boat building community on the west coast I’m flattered, thank you.
Since a $500.00 dollar build is pennies to you, and you are obviously challenging a building method you know nothing about I propose that you prove me wrong. Build 2 side by side plywood rowboats 14 feet long one using fibre glass and one using the GRC product. Have every thing else identical with the builds so it is a test of the product in question. Then prove to me that one is vastly superior to the other. I’m confident in the out come.

Dennis

 

You are really ignorant to some quite obvious level, but open your mouth as if you would know what you are talking.

It is not me to prove your wrong claims wrong! It is you to deliver.

And reply on this please:

Swain has done NOTHING positive to any boatbuilding community, quite the opposite! And that is a proven fact, you are well aware of! see:
http://www.boatdesign.net/forums/me...yacht-construction-248.html?highlight=origami

So shut your mouth before you spread more lies and dumb drivel around her, BRENT SWAIN!!!! (your dumb negative feedback comment and your stylometry exposes your real identity liar)

 

Richard this is someone who doesn't know or understand the physical properties of the products he's employing, let alone why they don't work well in combination. Asking for answers from these types of builders (term used loosely) is sure to bring more ridiculous and unsubstantiated claims.

Reminds me of a guy in Mississippi that built boats "his way" and insisted it was cheaper and stronger then the more accepted methods. He did this for years and nearly drowned one night when his boat literally split in two, while rafted up with another. Had he not been rafted, there wouldn't have been anyone there to rescue him. He posted here years ago (bragging about his methods), but hasn't since the "incident". I guess luck favors the prepared . . .

 

This is not someone Paul,

this is Brent Swain!

After being shot on the "Transverse Frames" and the "Origami" threads, he looks for a new business I guess.

 

I'm not going to get into the Brent Swain thing. He's got some followers on other sites and is well regarded in metal boat building communities. I understand your issues with him, but continued personal bashing is unproductive, ill advised and unwarranted. This thread's discussion can stand on it's own without it, in other words.

 

Sigh

PAR, well you bring up a good point. What I should have said was that I saw a production boat this summer that has GRC used as a non skid product on the decks, but I didn’t think to ask if it was original or did he add it I just assumed that it came with the boat. If I had said “now paint this boat with 3 coats of good boat paint” would you have kicked up such a fuss? The sheathing I suggested is low cost, remember the point of the thread, and durable. It is no more structural than the paint would be and the boat I pictured in my mind would not be relying on fibreglass for structural strength. As to you uncharitable remark about me being a “boat builder” your right I’m a light house keeper who has built or helped build 26 boats. Absolutely no qualifications what so ever to talk about it I should be ashamed of my self for even thinking of posting shouldn‘t I.
Here are a few pictures of some of the boats I’ve built. The first two are the first dory I built with GRC you can see the first coat of it hanging just after wetting it out, and before I put the second coat on. The second picture is the same boat 8 years later, just a week or two before some fellow with a 40 foot welded aluminium boat who was dragging anchor used it for a fender to keep him off the rocks, and crushed it. Taught my daughters to row in that boat, caught a lot of fish, and even did two rescues in it. By the way, to any one building a dory don’t put a motor well in it, it has too many disadvantages. The next one is two of the three canoes I built. Gotta love sanding if you wanna build that way. The third one is a Micro I helped my dad build, well many of the people in the photo helped. I can put more pictures up to further prove my ineptitude as I sort them out. Oh and I’m the guy in the blue hat. Does it make me look like Brent Swain?

Dennis

 

Hey Lampy

Those are some nice looking boats.I hope to post some pictures of my boat as soon as I can find a decent digital camera that dont cost as much as my boat.I would like to shoot some video and put it on Youtube.I recently saw a video shot of a national 12 taken with the camera mounted on a pole fastened on the stern quarter.IT gave a great perspective as if you were following along behind.They were HAULIN ***! My boat is not quite that fast but still planes like hell on a reach.I would like to do something like that.Have you ever done any sailing videos?

 

I have built several skiffs and dinghies with CDX plywood(carefully picked) and taped at the seams with mat and polyester. I see no need to fiberglass the whole thing. It is cheaper and lighter to use a thicker plywood. They last three or four years if left outside.

 

Saw, sorry no I don’t have any vids of sailing but hopefully soon. I just traded in some travel points for a good all weather cam that will make them. I designed and built a little dory for row and sail last year but I’ve been using it as a fishing boat and haven‘t put the CB trunk in yet. I have the sail cloth so I really should just do it. The other keeper here had a real crappy camera and took some vid of me building the boat, put it on utube. Picture is so bad I could be greasing the bottom side of a dog house and it would look the same. I think it’s at paulwhalentassis utube or something similar.
Gonzo: I agree! Before the popularity of epoxy there were a lot of boats built plywood on frame and painted and USED. It still works for the budget minded builder


Dennis

 

My little dory


Well, as it seems to be show-and-tell, here's a little dory that I built to Lampy's design. I did use regular fiberglass and epoxy to coat it with, though I think it's a bit of overkill. My other boat, is not one that I built, but is a homebuilt designed by Frank Carius, a NA from BC....unfortunately, it seems to be in a file format that won't copy to this forum. I'll do some more research. It used Dynel cloth in epoxy resin over strip-plank construction, seems to be durable enough. But in a design forum, on an inexpensive boat contest....it wouldn't rate.
I think the thing that we should be asking the professionals here, is how much of a boat they could design and build for between $300 - $500....and let's hope they can come up with something more than a radio-controlled model boat for the local pond.....

 

-very nice, LK!

I have a John Bull design for a sailing canoe, which I haven't built (not yet at least) but it also specifies the use of Dynel cloth. It is an acrylic resin and reputed to have great abrasion resistaince. Supposed to be hard to cut and needs a lot of epoxy to fill.

There are designs out there. I don't seem to have kept a record of cost but the little sailboat I built last year to one of PAR's designs cost around US$350 or so, including oars (Walmart) and home-made rig, so it's definitely doable. That's using respectable materials (marine ply, cedar, oak, pine, epoxy adhesive) but I did not glass it and the sails (tarp) were a bit less respectable I guess! It's only 10' (3 m) but should easily stretch to 12' within your budget limit, or the as-built size glassed. Of course, it depends where you buy your material; compared to Canada the US is cheaper but the rest of the world is more expensive!