Alternative hull reinforcement?

[Aquaholic]

Yo Peeps:

I've been adding layers of carbon/kevlar to the sides of my hull in an attempt to strengthen this old dog. I had some pretty substantial cracks develop in the usual areas, last season. Primarily on the top deck, middle of the boat, near the hood seal, resulting from numerous flopped, side landings.

I thought that I had things sorted out, only to be totally bummed after seeing new cracks appear so early in the season.

My idea is this...have any of you incorporated strips of aluminum with glass over that, to act as strengthening ribs for your hull?

I'll try to take some pics of the cracks...but I'm not sure that you'll be able to see them.

I've incuded some shots of some other reinforcing that I've done to the boat.

Thanks in advance.

Aqua

 

[RideItLikeYouStoleIt]

thats alot of resin....

 

[Aquaholic]

Here's some additional pics. Still kinda hard to see.

 

[CarterB]

ya...strength is more in the glass or carbon not the resin...try using a structural type of glass like biax 17oz

 

[sjetrider]

I take it you get carbon Kevlar CHEAP or FREE, why would you use it in hidden areas.

 

[Aquaholic]

I had extra carbon kevlar laying around from another project. I realize it was overkill.

From what you can see here....was this the wrong material to use, as far as strength goes? Did excessive resin make the repairs too brittle?

Is there any resolve here, or am I wasting time and $$ to try and salvage this thing?

 

[Matt_E]

Excessive resin is not good.

 

[FL-cracker]

I had extra carbon kevlar laying around from another project. I realize it was overkill.

From what you can see here;;..was this the wrong material to use, as far as strength goes? Did excessive resin make the repairs too brittle?

Is there any resolve here, or am I wasting time and $$ to try and salvage this thing?

It could have, but probably not. The upper hull right at the bondline is the problem area. Even when you reinforce on the inside, you can still crack this are.

The Material you used is very good for reinforcing, but you dont want exessive resin..... next time use a squegy, and scrape the excess back into a cup..... also Kevlar sucks to sand!!!!:banghead:

I am now in the process of reinforcing/ laying up the entire outside of my upper hull..... so far I have ground down all the Gel, and block sanded it out.... I reinforced the inside of my boat with pure kevlar <---- Kevlar is a bitch to sand..... I figured this was the only right way of doing it.... its extra work, but should be realy strong when complete... no more brittle polyester taking a betting..

I am gona use S-glass for this job..... its stronger then E-glass, and know were neer the cost of Carbon or Kevlar or Carbon/kevlar like you used,

 

[WAB]

Not questioning your work or ability....but how well did you rough up the hull before laying the material and how did you prep the old cracks? Is it just 1 Layer of material?

 

[RideItLikeYouStoleIt]

One layer probably should have done the job. I took my top deck off to reinforce and got all the way from top to bottom and up and down. I wrapped around the bond line too. Your ski is going to weigh a ton with all that resin and it isnt adding any structural support. Take a sanding wheel to that thing Pronto.

 

[RideItLikeYouStoleIt]

I was also thinking about some sort of aluminum supprts glassed in. I think teh route to go would be to just attach a support around the hood cut out. That is what weakens the hull. I was even thinking about putting in some kind of cross bracing under the hood and just have them removable for any work i want to do.

 

[Aquaholic]

Not questioning your work or ability....but how well did you rough up the hull before laying the material and how did you prep the old cracks? Is it just 1 Layer of material?

In retrospect I probably should have ground out the entire crack and used glass on both sides of the hull.

But, not wanting to do a repaint, I figured I could get away with just bolstering the inside. I think I used about 3 layers of cloth at the actual break area.

I thought that I had roughened things up sufficiently.

Regardless, I either used too much resin making it brittle, or didn't prepare the surface correctly and now the cracks have reappered.

I took the boat over to my fiberglass distributor to have them look at it. Their take on it was that the Carbon/Kevlar material is waaaay stronger than any conventional glass cloth...so it was either too much resin or something else?

I think my plan will be to thin some of that resin out with a grinding wheel and then glass in a few thin, aluminum strips.

That..and get my chit together on those botched landings.

 

[Matt_E]

What is that thing in your avatar?

 

[RideItLikeYouStoleIt]

i dont think more epoxy will hurt the strength. If anything add alittle bit more strength. Not alot but certainly not bring it down at all. I could be wrong but that just doesnt make sense to me.

 

[RideItLikeYouStoleIt]

that thing is his avatar is some hat that oakley sells. haha

 

[ChrisGooch]

What is that thing in your avatar?

http://oakley.com/category/684

 

[michael950]

$500 + $250 for goggles :bigeyes:

 

[Kny21]

http://oakley.com/category/684

Does anybody actually wear that crap?

 

[Aquaholic]

Ribbed for pleasure

Here's what I have so far. I roughed up the area with a grinder. Then I epoxied some thin aluminum strips in the cracked area. There's a very thin strip under the upper lip as well. I'll probably add two more strips extending down to the bond line.

Then I'll throw another layer of Kevlar over this.

The aluminum strips added minimal weight. Probably only 40-50 grams.

This may all just be a bandaid fix in the long run...If this old hull can get through the summer...I'll explore some options then.

 

[yamanube]

Isnt carbon much stronger than aluminum (pound for pound)?