Bell NorthStar weight and strength issues

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I don't know that CEW posts here. He does over at the ADK forum though.

I've also heard tell of boat manufacturers being a bit optimistic about their weights. I have a very accurate set of 0-200lb load cells I should weigh mine on. It would be interesting to see how much Swift exaggerated on my Kee.

FWIW Mr. Curtis weighed my Eagle in at 64lbs before I bought it and my Swift feels significantly lighter, so it may actually be close to the quoted 40lbs.
 
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Why are you sitting in the canoe in your back yard??CEW would have a fit. Of Course the boat flexes then! And yes you can break it that way. Never never sit in a boat on a hard surface.

There is a ten percent variation of hull weight that is acceptable. You don't specify which portage pads you are using and the wide seat has to add several pounds. Your boat was designed to be a tandem and has extra stiffness at the ends. With a center seat you are pulling in the sides of the boat where they are not reinforced. You should consider adding a pedestal under the seat to support it.
 
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Those pads are not light. I am guessing your boat is not overweight. When you test sit on dry land all boats are going to flex as Archimedes law cannot respond(weight of water is displaced by weight in the boat and of the boat). Water actually supports some of the bottom from the side to three or four inches.

BTW if you have good strong gunwales ( and you do) the layup is fine. There are eight lb boats made out of a frame with plastic wrap that do just fine with a kneeling paddler. You can google Platt Monfort Geodesic boats.

I have used a friends NorthStar for solo paddling and teaching Canadian Style. Its a Black Gold and I really don't notice excessive flexing. I just borrow it when needed maybe once a year.
 
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You have Kevlight? Not so much material in the sidewalls at the center. Can you see how many layers of fabric you have toward each station (bow and stern) and how many in the middle?

I don't think I have seen Kevlight with wood rails. Sure it exists, but I have never seen them.

I would try out your boat as is.. and if it makes little cracking noises..it will give you warning. If you make a pedestal make sure you spread out the weight of the foot a bit or use minicell which has a little give. What you don't want is punching a hole in the foam core.
 
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Kevlite and wood rails do exist - had a Merlin II in that configuration.

I'd second the use of mini-cell foam for the pedestal. Its impact absorption is made to order for this application. The ability to customize it via carving is limitless. M-200 is the more dense version of minicell and would be ideal for use as a pedestal. Its available in a 3.5" thickness and carves wonderfully.

M-200 can be hard to find but I've purchased it previously from One Ocean kayak:
http://www.oneoceankayaks.com/cgi-bin/web_store/web_store.cgi
 
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Two minicell blocks ought not to weigh 5 lbs. I have a whole chunk in the garage that is unwieldy and about two by four feet. It is five lbs. But you don't need that much. Even one slide in block of minicell that you wrap your feet around if kneeling would suffice.

Go paddle it. I think this problem might not be a problem. Have you fallen out of a canoe and noted the movement of your feet? Unless you have fused ankles, entrapment is less likely than you think as your feet rotate.

There is naturally some give in most boats that are not stiff racing machines. And check out Wenonahs tractor seat attachment. Wenonahs are known for UL layups and I doubt they would attach their tractor seats to the bottom if it compromised strength.

Your chief concern is not outward bowing. Its pulling the rails down.
 
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I doubt you are going to have much issue in the water. I too would never sit in my boat on land for fear of it cracking. YC said it, I'll say it a different way. The water pressure adds compressive stress to the outside of the hull up to the water line where normally will have tensile stresses from the seat load. All in all the stress (and thus deflection via Hooke's Law) will be less.

Stress is the real concern as you don't want to crack. A little flex is good to help absorb some energy on a small impact. Too stiff can mean less deflection but more prone to stress cracking.

One other area to look at is your seat connection. I should draw a diagram to explain this but I'll try with words. In order for your gunnels to flex in and your hull to flex out in bending, the seat and the hangers must also bend and shorten the span. This is why a center column support would work, because it connects the area of greatest deflection of the seat to the bottom of the hull, which is supported by hydrostatic pressure in the water. One can also decrease deflection of the center of the seat due to bending by stiffening the hangers and the connection to the seat.

The other area would be to put small strips of foam right in the corners of the bottom of the canoe, not all the way across to locally stiffen the chine area. Right below the water line is where the moment and thus the stress will be highest. This is what you will typically see on a Wenonah or the like to stiffen the waterline area. They do this primarily to reduce hull deflection while moving so as to keep the hull efficient. They are also more likely to crack in the those location though because the stresses increase in an impact and the energy cannot be absorbed.
 
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Try it in the water and see how it feels... best not to over-engineer it.

I suspect your layup is similar to my Swift (it may not be but I've poked at a few Bells and they feel similar, quoted weight is similar as well), if that is the case I too have a kneeler installed and weigh much more than you (about 50 lbs at the moment) and have no issues. The boat does flex, but not in a bad way. It is all elastic deformation and nothing that is causing cracks to form.

Mine does have some reinforcement 'ribs' - I'm not sure how much they do as they are only single layer, 3" wide strips that run about halfway up the hull from the foam core. There are maybe 5 spaced evenly along the length of the boat.
 
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I suspect your Wenonah has Kevlar over foam ribs, which will make it significantly stiffer.

Mine are a single ply of Kevlar. Very minimal stiffness increase but could be a significant increase in strength.

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Some carefully placed strips like those near the seat could be beneficial. I doubt it will add much stiffness, as you only increase the thickness marginally, but the added strength could be a benefit in the future. FWIW none of mine are aligned with any of my seat hangers or my kneeler (which wasn't installed when I took this picture).
 
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We can all conjecture and I have paddled a slew of Bells over the last 15 years and not seen material failure..even using the center thwart for Canadian Style! You should probably ask the guy that most likely built it.


charliewilson77ATgmail.com

Bell boats pre ORC were the best built boats around.
 
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Yeah mine has what Swift calls a Clear Coat. It isn't as heavy or tough as a true gel coat. If I had my choice I'd have this clear on the sides and a white gel coat on the bottom. Not surprising, this is how Hemlock is doing their Premium + boats to save weight without sacrificing scuff resistance.

The other boat is a glass and kevlar Eagle. It is a bit heavy but tough as nails.
 
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I think ORC was 2006 but don't hold me to that. It was after 2000 but I don't really remember how long. That kind of puts your situation in a different light.

Skin coats can be epoxy (Souris River) but not all are. Wenonah uses a vinylester resin. I think Swift uses a clear gel coat as does Placid. Charlie would know that too.. he is currently a consultant for Swift. LDC is using the colored gel coat (rather than tinted) that we are most used to. I think its true that different makers use different thicknesses of gel coat. My Rapid Fire has nowhere as thick a gel as is on my yellowcanoe which is a 1993 Swift. Back then the UL thing really had not kicked in.
 
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Yeah most Kevlar boats I see from that era are mid 50's... now that is considered fat!

In that case I might be considered trim by 20th century standards :D
 
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I've had an extended conversation with CEW about this issue. He gave me quite a few good ideas and I learned a lot. When I told him the flex (about 1/8" on each side) happened when testing on a hard floor, he said, "you have no problems to speak of." If he had a fit (as yellowcanoe predicted) he didn't let on.

I guess I don't need to worry about it.


He likes a good Cabernet. Never a white. Really he knows more about canoe construction because that is his living. The rest of us are more or less educated spectators. I can' t control other actions but can sometimes give a more or less accurate guesstimate. He is a personal friend of mine but I can't guarantee action or not as the best I can control is my own action.

No you don't need to worry about it.
 
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