Am I wrong to believe that foam core construction is inferior to solid cloth laminate in terms of strength and repair . specifically swift and h20 both use
full bottom foam core , where as souris river have solid cloth with foam ribs
and, millbrook is all solid clth laminate . I want a composite prospector to use in
white water like palmers rapids, spanish river , petawawa . I dont expect a composite boat to survive a wrap but I know it will get a beating with fast impacts
and gouges from submerged rocks and shallow rock gardens. should i be concerned about repair issues with foam core contruction.
thanks mark

My personal experience is that you are correct -- most WW composite boats (like Andy Convery's new Echoee) do not have a foam core). You should post your question on Cboats.net as this is where most of the people with WW composite boats hang out (including Kaz from Millbrook).

thanks peter i'll check out c boats

I would agree with Peter K. The purpose of foam cores and ribs is to add stiffness without adding as much weight as using cloth and resin would. But foam has much less strength than resin-impregnated fabric does. All of the composite whitewater boats I have personally encountered such as the Millbrook boats, the Clipper Duraflex Vipers and Probes, and the Hemlock Shaman are all-cloth construction without foam cores and ribs.

I do have a whitewater canoe that has a bottom core and side ribs which is a Mad River Twister. This canoe was designed as a very lightweight slalom racer. The boat developed cracks all along the edge of the bottom core as a result of the stress riser created at the junction of the stiffer core and the less stiff hull. The boat has been extensively repaired with Kevlar and is now sound, but considerably heavier.

In other words it sounds like once you have made a composite boat tough enough for whitewater, you have enough layers of cloth & resin that the hull is already stiff enough and there is no longer any benefit to including a foam core?

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More or less. The only purpose of a "skeleton" of foam cores and ribs is to allow an acceptably stiff hull with less weight.

Stiffness of a hull is largely a function of thickness. Bottom cores and ribs of synthetic foam or balsa add considerable stiffness with much less weight than multiple layers of resin-impregnated fabric would, but they add little, if any, strength. And they create stress risers along their margins. In whitewater, hulls will flex considerably. The areas of hull that incorporate core materials flex much less than the adjacent thinner hull and cracks occur along the junction as a result.

In the event of a through-hull crack, foam bottom cores and ribs complicate repair somewhat.

pblanc and splake thanks for your replies
what u are saying re enforces my thaughts on the subject . Im willing to carry more weight in canoe construction if it means a tougher hull and easier repairs.
My current canoe is a nova craft 17 prospecter in royalite and it has held up well
for the last 15 years but it does have a few g flex repairs and skid plate patches.
I'm thinking that all the repairs are epoxy and cloth on a plastic hull , so why don't I just get a composite boat for better repairs.
know shopping for a 16 prospecter with the least amount of foam
thanks again mark

I have owned three foam cored Kevlar canoes built by Mad River during the ~1990s, an Explorer and Horizon in what MR called the 'Kevlar Expedition' layup, and a similarly constructed Independence solo canoe. All three are extremely rugged, durable canoes. The Independence needed repairs but survived having a full sized tree land on it during a winter ice storm in 1998, and is still being paddled today. The Explorer and Horizon had published weights of 51 and 54 pounds, respectively. I have bounced the Explorer hard off plenty of rocks on bonier whitewater runs. Mad River in those made-in-Vermont days was using vinyl ester epoxies and layups that have proven quite durable in terms of combining strength and enough flexibility to survive impacts. Vermont has a lot of rivers and few lakes. Mad River's competitors in those days for composite tripping boats were Bell and Wenonah, both of which grew out of lake country and flatwater racing traditions that valued light weight and rigidity. I have also owned two Bell tandems from the original Bell canoe company. At 35 pounds (with foam core bottom and ribs) or so the Northstar is light, stiff, and fast, but it is not what i would call a rugged canoe. I've not experienced breakage or separation related to the ribs, but the bottoms are soft compared to the Mad Rivers, easily creased by a passing rock, a difference due to the extra ten or 20 pounds of Kevlar and epoxy in the Vermont-built boats. I have friends who have paddled their Mad River Explorer across 1000s of miles of Labrador and Quebec.

What did you end up buying?
Sounds similar to my interests of whitewater tripping.
I'm looking at an H2O in Brute Force which I think uses a foam core and a Nova Craft which I think is a solid laminate in Tuff Suff.

Good day. Donomemee
I bought a Souris River 16' prospector with an extra kevlar layer. It was a heavily weighed decision. I like the Nova craft -Moise but the tuff stuff has a foam core and they don't use epoxy resin. H20 on their website push epoxy as the best stuff for canoes, then go on to make the brute force with corshell vinyl ester to keep cost down or something,But also has a foam core . I will say they make a nice canoe and surely know more than I about laminates.
Souris River does have foam ribs across the bottom but they are added on top of the hull laminations and not integral to the hull. They also use epoxy resin ,And have a good reputation for durability . Their prospector design seems ideal for my needs. I bought it at the adventure show in Toronto last month and should get it in early may.
You may want to look into the Echo - starlight I didn't know about it until after my purchase
so never inquired about construction . Clipper canoe has a solid cloth laminate and I think Millbrook does too.
Good Luck. hope to see u on the water

Thanks Mark.
Was at the show to and talked to Jeff from H2O and they have switched to all epoxy for their Brute Force layup.
I don't want a total whitewater boat so the Starlight wouldn't work.
It's a copy of the old Evergreen Starburst, which I paddled on my whitewater course at Paddlers Co-op and I'm leaning more towards tripping than all out whitewater.
A Prospector or crossover like the Voyageur is what I'd like.
Like U it's a tuff discision.
I'm gonna test paddle a few and decide.
Happy paddling.

......

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Hey Sam, why don't you let me help you out and take that god damn Scout off your hands.

Hi Sam. I fully understand your point of view on bringing a composite canoe on a remote white water trip . As for boat design , I actually like the prospector . In comparison to what I have paddled , dumoine , canyon , quetico , and different prospectors . I know not a long list.
I don't have any plans for remote trips my kind of thing is 3 - 4 nights in Algonquin , French R Spanish R , and some weekends at Palmers Rapids. I do enough flat water fishing and portaging that royalux loses its shine . Which is why my first canoe was royalite . Im hoping the Souris River with an extra kevlar layer will be just as tough or tougher. fingers crossed !

I sort of got onto a rant there lol. I have plenty of respect for the Prospector design...lots of history there. I just prefer different designs to excel in whitewater over flat and I don't see a composite boat designed for lengthy whitewater solo trips.

The Souris boats look beautiful and one day I'd like to have one of their ultra light layups for flat water/portage trips. Will have to save up for that purchase!

Enjoy your new boat I'm sure you will love it!!!

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