vacume form canoe
vacume form canoe
(OP)
has anybody tried vacume forming a canadian style canoe? about 4m long x 900mm wide by 580mm deep. I was thinking of using 10mm thk HDPE sheet...
any suggestions would be gtatefully recieved
any suggestions would be gtatefully recieved






RE: vacume form canoe
Here's a "Canadian Style" canoe molded in two parts in FRP:
http://www.blackpete.com.au/bp_canoes.html
The gunwale seam would be a problem in HDPE, because adhesives and sealants don't stick to it. You'd need a gasket and a lot of mechanical fasteners.
How about a nice double ended dory?
Mike Halloran
Pembroke Pines, FL, USA
RE: vacume form canoe
I assume the Royalex(tm) canoes are thermoformed - cannot see how the stem and stern are done though....
htt
Cheers
Harry
RE: vacume form canoe
ht
In which case it would be possible to inflate the hulls in the un-obvious way. I have no evidence that Old Town actually does it that way; it just seems a possibility.
It doesn't seem possible to vacuum form such a hull in the obvious way, given the recurve at each end, and the relatively fine radius at the stem.
The vinyl/ABS/ABS foam/ABS/vinyl laminate would surely produce a much lighter hull than 10mm of HDPE.
Mike Halloran
Pembroke Pines, FL, USA
RE: vacume form canoe
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: vacume form canoe
If you start with 10mm HDPE, I'm estimating > 100lbs for the hull. No way would anyone portage the damn thing.
Mike Halloran
Pembroke Pines, FL, USA
RE: vacume form canoe
so yes they have to be very rhobust and im not too concerned about the weight, (i worked it out to be about 29kg, 64lb in ye olde weight)
my main concerns are that the bow and stern are going to be stretched the most, therfor thinner wall thickness and weakest area that is going to take the most damage...
the gunwhale, im looking to bond and fasten strips of spare sheet, after the canoe is formed. What is the best method for bonding HDPE to HDPE?
Thankyou all for your valuable input
RE: vacume form canoe
3M make some adhesives that work OK if applied under ideal conditions.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: vacume form canoe
it needs to be hardwaring and scratch resistant, low water absorption, easily formed, easily bonded, good UV properties, and cheap
RE: vacume form canoe
Under nonideal conditions, e.g. with scouts, you can't bond PE to PE, period.
If you can do without the recurved ends, i.e. everywhere concave up, and use a generous radius at the stems, you could use HDPE. It would look more like a skinny dory than a canoe. You could probably use sheet as thin as 3..4 mm if you flange the gunwales.
Or you could use HDPE, blanked to the shape of a birchbark canoe, with recurved ends, but each end would have a vertical stem seam that must be caulked or gasketed and have a mechanical retention means. Use a row of bolts and nuts, or lace it with wire or fishline.
Instead of making the canoes durable, you might consider making them disposable, or at least constructed from cast-off materials. They are using more stretched fabric these days, but billboards and signs used to be constructed of masonite or galvanized sheet steel. Maybe you can locate a source of used sheet ... something ... that could be adapted.
Mike Halloran
Pembroke Pines, FL, USA
RE: vacume form canoe
RE: vacume form canoe
For abrasion resistance, PE strakes or external stringers could be bolted on.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: vacume form canoe
------------
Jason Williams
K Development, Inc.
RE: vacume form canoe
On the "other materials" topic, HDPE canoes are pretty nice, but heavy if they are to be durable. If I had the time, $$$, and wanted to build a class III capable canoe, I would find a good "fiberglass" mold for the style of canoe I wanted, and then read up on using either an epoxy/kevlar or a urethane/kevlar system instead of glass fiber. You can form some pretty complex shapes in an "open" hand-laid mold.
There are several local river boat races around where I'm from, which are usually won by people with home-built boats of the above materials. These races typically take place on class II and III rapids. Some of the winning hulls appear to be ~1/8 in. thick, extremely light, very supple (the hull can buckle over rocks/tree stumps without creasing/cracking) and strong. At least, that's what I could see from my old fiberglass tub, as the winners streaked past...
I really do like Pat's suggestion too, of a keel strake (or multiple strakes) of poly that are bolted or...dovetailed? on in some manner removably mounted onto the hull for abrasion resistance. Once they've started to get really scuffed up, you could strip it off and attach fresh grind rails...
RE: vacume form canoe
All rotomoulded canoes I saw were simple basic designs with relatively level gunnel's and stems and sterns.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.