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Permalink Reply by chris towles on October 24, 2011 at 7:36am

A few thoughts:

1. Multiple layers of triax might be overkill. most use one layer of 6 oz reg weave on the sides and 20oz of glass on the bottom. Depending on the weight of the triax, 2 layers on the hull could be ok, you might be fine with 6-10 oz on the sides.

2. Don't glass over the chine batten, it's meant to be sacrificial. At some point with those hard angles you are likely to put a small crack in the glass and water will find it's way in. Once it's in there rot will start. Sounds like you have already seen this in action. use a hard wood like white oak, mahogany, or ipe. 1/2" to 5/8" strips. Cut an angled bevel or use a large roundover on the top to help combat chine dip. Keep the bottom sharp. Use a bedding compound to seal it. I like sikaflex 291, it has better adhesion than polysulfide caulks, has greater flexability, and is easily removed mechanically should you need to replace the batten again later (I like a high e guitar string and a razor to remove excess of the surface surface after the batten is removed). Others have their opinions as well.

3. No chine batten at all ? That could work also. You wont find many of the traditionalists here reccomending that though. Sttich and glue boats have no batten, however due to their epoxy jointed chine seam they may arguably have a more rugged joint in that area. If you do it, make sure to use a few layers of glass tape over the joint. Biax if possible. And be ready to do chine repairs if you do have an eventual hard encounter with a rock. Aside from that , it should probably work fine.
Chris

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Permalink Reply by Jim Philpott on October 24, 2011 at 9:13am

So since it is a framed boat and there is no fillet along the inside joint that outside chine batten does have some structural significance?  I kind of figured that but wanted to put it out there just in case.  

 

With the bedding compound that you recommend, does that act as a sealer when attaching the batten with screws? 

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Permalink Reply by chris towles on October 27, 2011 at 1:12pm

I tried leaving a long reply a few days back, but my phone lost it before it ever got to the board.

Yes... I should have rephrased that last line of my last post.  It should probably be fine until you hit a rock. Obviously the thicker the material at the joint the better. 3/4" log plus 1/4" ply is 1" thick joint. Add a 5/8" batten to the outside and you have a joint almost 1.6 as thick. In my opinion the batten isn't necessarily there to add strength to the joint to hold it together as it is to be a bumper in the event of an impact. Iike the one on your car, it allows you to whack into something and potentially not Damage body panels or worse your frame. It's sacrificial remember..breaking this piece first means  Mabye your ply  will see less impact and not break, or break less. As aj said, stainless half round or a strip of aluminum or uhmw  will cushion the impact a bit more before the energy gets to the batten and the side panel. Last season I tagged a rock hard in a wavetrain. Never saw it and I hit it hard with a loaded boat. The energy blew my batten into 3 pieces., however it was bedded well with alot of sikaflex (very flexy caulk). I think the batten blowing apart and having a bit of flex with the caulk is what dissapated the energy and saved my bottom sides and even glass from suffering any damage from that impact . I had two little cracks in the glass at the impact point. I injected the cracks with epoxy, cut a new batten, ripped the old one off fairly easily, and threw the new one on w bedding.. Total time 4-5hrs probably. I was back on the river a couple days after the repair (had to wait for bedding to cure). Please don't think I was recommending that method of no chine cap. With a framed wood boat, you Definatly want it there. I'm positive  you could probably make a heavily taped joint work with enough material... Fiberglass is pretty amazing stuff. But the amount of time, money, and effort required is way too much, and in the end there is not too many good reasons to do it. you certainly wont gain any strength or make repairs easier, so why bother. The traditional methods are quick, easy, and cheap...and they are proven to work in your application. Just bed the chine and screws well and you should have no problems.

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Permalink Reply by lhedrick on October 24, 2011 at 7:45am

You won't be able to replace the cap after it's all glassed.  

 

In order to glass over the outside chine edge you will need to round it over.  About the curve of a quarter or half dollar.  Your are talking about what we do in stitch and glue construction but there is a big difference.  You wont have any glass on the inside.  

 

I don't build framed boats but from the past I do know that it is the inside and outside strips which lock the joint with screws going all the way to the inside.  Since you won't be doing the inside this method may not be the best idea for this boat. I just have not done it.  Not sure the joint will be what it should be with no locking screwing going into the inside member and there will be no fillet and glass to bond it together on the inside and seal it off from water.

 

If you want to glass the sides and bottom you may wish to glass to the edge with no round over.  When done install new outside caps with removeable sealant and don't glass over it.

 

 My guess is that many layers of side glass going over the chine and lots of heavy biaxial tape should be okay but, I have a feeling that with no glass epoxy seal on the inside water will find it's way to the plywood and cause trouble.  Hopefully the other framed builders will have something to add to this idea.

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Permalink Reply by Jim Philpott on October 24, 2011 at 1:55pm

Thanks for all the info Guys!!

 

Cheers, 

 

Jim

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Permalink Reply by AJ DeRosa on October 27, 2011 at 5:50am

I'm the traditional guy and , as advetised, I would never recomend leaving the chine cap off of a traditional frame built boat.  The inner chine log and outside chine cap work together to create the stongest possible chine joint.  A stip of metal in the impact area makes it even tougher.  Why anyone would consider making the chine weaker is beyond my understanding.  This is the area of greatest abuse and it needs to be as tough as posible.  The combination of outer chine cap and metal strip distribute the impact across a greater area in the event of a hard hit.  Hard hits happen, even to the best of boaters.

The stitch and glue guys build a very strong chine with lots of glass and epoxy but that is backed up by a generous fillet on the interior that is also reinforced with glass tape and epoxy.  Inspite of this most admit that this is the area that gets repaired most often as the glass can chip and crack.  A crack in the glass here, below the water line will wick in moisture.

My advice to framed boat builders is to stay true to the traditional techniques, they work well. 

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