C-Forum

Rather than thread jacking Bahndo i thought I'd start a new one

How important is it to reinforce the bottom of a creek boat? Is just the structural rail enough for the boat and for your protection or do you reinforce with a 2nd layer of kayak hull or do a fancy kevlar layup?

I've felt a few rocks through the Cascade side wall where the seat doesn't add reinforcement.

Gabe

((didn't want to hijack the original thread either))

a couple of thoughts in general (not necessarily mine):

doesn't anyone worry about creating such a immovable stress riser and wouldn't a thin 1/2' or so of layer foam under the backbone help diminish this... a plastic welding buddy (Mark Cumnock) has noticed failures next to areas where people are making hulls rigid

another point that was passed on to me years ago from Roger Scott (of Occoe land fame) is how sand wears out HDPE hulls from the inside out... when he did kayak outfitting he would always adhere foam to bottom/inside of hull - under a seat.. that way he maintained the sand was grinding away on top of foam... he claimed it made hulls last a lot longer, as you couldn't keep sand from accumulating there... so i'm guessing there might be a need to adhere the backbone entirely along bottom, so no sand can get under... at least maybe a bead or fillet joint of silicon

I've seen a few boats break along reinforced areas. The one rail design in the Jacksons is where all of the bad blue boats break. (Say that 5 times fast!)

A buddy of mine completely re-did the yak outfitting in his Draggo Rossi. It was all foam with an 8" or so wide piece of wood for rigidity where the plastic seat was. He foamed underneath the wood and it still cracked the hull the first time he paddle it. He was comfy while the boat sank though.

Isn't it important to at least leave the rail that the seat mounts to for the structural integrity of the boat? Especially in a creeker? Lay down sheets of 3/4 the length of the cockpit and sidewalls for impact protection?

What do you do Larry? Probably too busy creekin to get online....

The last boat that I converted (A Dancer - it was a looong time ago...), I ran a "droopy" ladder made of aluminum tubing from the front deck to the rear deck. It was about 4" above the hull where it passed under my seat, which I made to fit in and around the tubing. The foam passed all the way down to the hull and kept the hull from oil-canning (with some give built in). The tubing was there as a place to fasten the thigh straps and to stabilize the seat from side-to-side.

It helps if you can weld aluminum...

structural foam spine... foam, foam, foam... FOAM!!! http://boatertalk.com/forum/BoaterTalk/1425641


here's a recent playboat i did for someone... this is all rough cut and not tailored to fit the occupant yet. i make a foam center spine that runs from bow to stern and sandwich it with two more 3" pieces on both sides and build the "bulkhead" from there. in this boat like mine it will use a lap belt and kayak airbags to compress the knee's and lock them into position (not for use in a creekboat but you get the point). patent pending

I imagine the stress riser caused by foam would be less significant than that of a stiffer material... And if not glued in, the abrasion due to sand would certainly be less significant as well...

How do the float bags work in your system? What are the pieces of wood for?

Q

oopsiflipped wrote:How do the float bags work in your system?

AQuite Well

Q

oopsiflipped wrote:What are the pieces of wood for?

AThose are the wood gunnels... that's what makes it a canoe



pm me for more...

I just picked up a H:3 and am having plenty o trouble finding a square pvc tube to build the spine. This is a big boat (255) and I am a big guy (235 lbs). I want to do a full foam bulkhead. Will foam bow to stern be enough to stiffen this boat or should I use some sort of plastic reinforcement? Any tips, photos or otherwise useful information would be appreciated.

I like the square PVC downspout - it's smaller and doesn't take up as much space in the cockpit. If you don't think it is strong enough, you could reinforce it internally. I saw somebody do that with a beam built up from marine plywood and sleeved with the downspout.

Craig - where the water bottle go - or do you only paddle in clean water

philcanoe wrote:Craig - where the water bottle go - or do you only paddle in clean water

[img]http://www.zymetrical.com/images/produc ... helmet.jpg[/img]

am having plenty o trouble finding a square pvc tube

I use Vinyl Fence Rail, Purchased at Lowes or Home Depot, About $13 for 8 or 10 feet woth. Found in the Garden dept. Have used these in m,ultiple boats works great and is plenty strong.
B

My opinion is you must reinforce the hull when you take the kayak seat out. It prevents oil canning of the hull but most importantly it will make the boat less susceptible to wrapping. If the boat is going to be used for float and bloat flat water trips or just park and play then it is not as important, but if you have the intention of paddling on a river with current and rocks then it is a real safety issue. Just my opinion but test it out for yourself- take the seat out of a kayak, place the boat on fallen tree, bench of something similar, have a friend sit on one end and you sit on the other. Try it with the seat in first as the boat may fold enough to crease.

As for the stress riser issue-
If you support the hull with something stiff that does not give your boat will wear out faster and/crack in the area of the support. This is because the boat is no longer able to flex and absorb impacts from rocks. The ideal setup is to have a nice stiff spine support trimmed with 1/2"-3/4"of mini-cell that is just slightly preloaded upon installation. Hope this helps and good luck,
-Bahndo

sbroam wrote:... And if not glued in, the abrasion due to sand would certainly be less significant as well...

actually thinking that without glue sand can/will get under or inbtween... while if structure is adhered, then sand cannot get there