Hull Hook Repair

[Yesterday]

I have an old Chrysler tri hull I've been rebuilding for a number of years. I had it on the water for two seasons when I discovered something nasty. Because it sat for years with the transom hanging over the bunks of the trailer and had a large O/B motor installed. The transom sagged by about 3/4" and I not knowing better, assumed the shape was they way the boat was made. On top of that, I had to replace the keel, and it looks like the bottom of hull on one side was uneven when everything was rebuilt, leaving the rear part of one half of the hull, lower than the other by about an inch!

I thought about using filler it but 1" is a bit extreme, so here is a potential plan:
The boat is upside down so I can work on the hull. I thought I might cut the hull at its lowest point on that half from the side to the keel (about 4" ahead of the stern) and lift up on the hull in the hooked are pulling it out. I would then use expanding closed cell urethane foam to fill in the gap, and once it's set up, I could repair the cut I've made.

Does this plan sound reasonable? If not any suggestions? If yes, any helpful tips? I hate the idea of cutting the hull but Im not sure I have any better alternative choices.

 

[redfury]

Re: Hull Hook Repair

You could always just grind around the hook, fill the gap with balsa and then glass it smooth. That way you'll still have the glass from the original hull, and you'll fix the hook with minimal fuss or added weight.

 

[Yesterday]

Re: Hull Hook Repair

Hmmm so effectively using the balsa as a form to extend the hull out, that could work. I may even have some Styrofoam (intended for that purpose) I can use. Either way it's a viable alternative for sure, though that may be considerably more work?

Last night I revised my original plan to simply making about a 4" cut and sliding an aluminum plate between the hull and flotation foam, to use as a puller. I just don't know how much of the hull would come back up to the right position. Now I have an alternative to consider, I'll give this some thought. In the interim, I'm attaching a picture though hard to see, to give an idea of what's going on.

 

[redstrat]

Re: Hull Hook Repair

It's hard to tell by the photo, but I think I would consider cutting out a section of the floor, pushing it back into shape, and reinforcing it on the inside. How do the stringer come into play?

 

[GT1000000]

Re: Hull Hook Repair

Just a thought, but the idea you have of sliding an aluminum plate between the hull and the foam might work if you apply heat to the affect area while creating an upward pull through the aluminum...maybe by using a pry bar under the aluminum to push up while applying heat
My thinking is that fiberglass is, after all, a Plastic which is reinforced with fibers, by gently heating it with a heat gun, it should become pliable enough the flex back into shape...then inject some foam to stiffen it up...
I would love to see what you come up with to solve this...
Best of luck!
GT1M

 

[Woodonglass]

Re: Hull Hook Repair

ON the Fiberglassics.com forum I read a thread where a guy used a bunch of bricks inside the hull over the hook area then drained the water from his Hot water Heater into the hull and boiled 5 gallons of water using his outdoors Turkey cooker. the heat of the water and the weight of the bricks on a hot summer day took the hook out of his hull. As the water cooled the glass set back to the original form. He then glass the inside of the hull to reinforce it. Worked for him.

 

[Yesterday]

Re: Hull Hook Repair

It's hard to tell by the photo, but I think I would consider cutting out a section of the floor, pushing it back into shape, and reinforcing it on the inside. How do the stringer come into play?

I had thought about that but the stopper for me is the fact that just prior to discovering this hook issue, I just replaced the floor and carpet - brand new! tearing up the newly laid carpet didn't sit well with me, though maybe my logic is skewed by emotion here! LOL

Aside from the keel stringer, there are none in this boat, sub-floor. It's all (new) foam.

 

[Yesterday]

Re: Hull Hook Repair

Just a thought, but the idea you have of sliding an aluminum plate between the hull and the foam might work if you apply heat to the affect area while creating an upward pull through the aluminum...maybe by using a pry bar under the aluminum to push up while applying heat
My thinking is that fiberglass is, after all, a Plastic which is reinforced with fibers, by gently heating it with a heat gun, it should become pliable enough the flex back into shape...then inject some foam to stiffen it up...
I would love to see what you come up with to solve this...
Best of luck!
GT1M

I was thinking about the whole heat gun issue too, wondering it it would help. I think I will try that tomorrow. See following update

 

[Yesterday]

Re: Hull Hook Repair

ON the Fiberglassics.com forum I read a thread where a guy used a bunch of bricks inside the hull over the hook area then drained the water from his Hot water Heater into the hull and boiled 5 gallons of water using his outdoors Turkey cooker. the heat of the water and the weight of the bricks on a hot summer day took the hook out of his hull. As the water cooled the glass set back to the original form. He then glass the inside of the hull to reinforce it. Worked for him.

This would have been perfect last summer before I re-foamed the entire sub floor. Good info/idea though!!!!

 

[Yesterday]

Re: Hull Hook Repair

So here's my update: I thought I would make a puller of sorts from 2 angle braces and some threaded rods, to get a general feel for how it will work, only making 2 small cuts through the hull. The hull distortion on one side is way worse than I originally thought, and the puller looks like it will negate much of it leaving a smallish hook to fill. I'll post pics shortly. Keep in mine I've not yet applied any heat. Interestingly, this gizmo is lifting the weight of the whole boat, which is acting as a limiter for me and something of a safety.

 

[Yesterday]

Re: Hull Hook Repair

Note - The L brackets are facing away from each other, and the length along the inside of the hull is the same as the perpendicular heigths.
Closeups:

 

[redstrat]

Re: Hull Hook Repair

I had thought about that but the stopper for me is the fact that just prior to discovering this hook issue, I just replaced the floor and carpet - brand new! tearing up the newly laid carpet didn't sit well with me, though maybe my logic is skewed by emotion here! LOL

Aside from the keel stringer, there are none in this boat, sub-floor. It's all (new) foam.

Gotcha. That would make me think differently as well. I'm thinking of how to apply heat. Maybe a box structure and a salamander style heater? Most things that get deformed want to get back to there original form. How will you break the bond between the hull and the foam?

 

[Yesterday]

Re: Hull Hook Repair

So, the results are in!!!!
After re-aligning this hull I did some testing yesterday. Same motor & prop, place and conditions as previous tests:
Previous top speed: 44 km/h @ 5620RPM
New Top speed: 49km/h @ 5820RPM

So I tried another prop 2" pitch higher. Last year it laboured badly with this prop and did well to hit 4600 RPM WOT.
This year, it topped out at 5300 RPM though still topped out at 48/49 km/h

**note** All speed figures are GPS.

The boat handles way differently and tends to keep it's nose much higher.

 

[GT1000000]

Re: Hull Hook Repair

Most excellent news!
Now, details of what and how...
I know you used the L-brackets and suspension, but did you apply heat or just let it hang?
Spill the beans, man...

 

[Yesterday]

Re: Hull Hook Repair

Most excellent news!
Now, details of what and how...
I know you used the L-brackets and suspension, but did you apply heat or just let it hang?
Spill the beans, man...

I did use a heatgun and gradually heat the whole area, paying particular attn to stress points given the hull's shape and while it did seem to give it a bit of extra elasticity, I'd have to say the effects weren't huge. It might have given me an extra 1/8" perhaps? I did try to add more tension on the puller after heating. If anything it seemed to help round it out a little bit more.

I pulled it, foamed under, then I dropped two layers of some new fan-dangled fiberglass which was a woven cloth/mat combo (Thick and not overly expensive) and then I made up the difference with just shy of a gallon of filler.

I should also note that because the hook was different on both sides, and now the hull is far more balanced/uniform, the crazy torquing it used to do to one side, is also now gone.

per the linked video, from standstill to WOT the boat would nose up, nose down and then twist, if only one person was in it. I thought it was a prop rotational thing being a bit on the severe side, but it was produced by the hook.
http://s1243.photobucket.com/user/f...eforeampAfter_zpsbf341b93.mp4.html?sort=6&o=0

 

[Yesterday]

Re: Hull Hook Repair

Gotcha. That would make me think differently as well. I'm thinking of how to apply heat. Maybe a box structure and a salamander style heater? Most things that get deformed want to get back to there original form. How will you break the bond between the hull and the foam?

Sorry I hadn't seen this question earlier. There was little to no resistance between the hull and the foam. Given the amount of tension I applied I expect it ripped away fairly easily.

 

[GT1000000]

Re: Hull Hook Repair

Thank you for sharing and the video looks like it is running nice and smooth, congrats on a job well done!

 

[Yesterday]

Re: Hull Hook Repair

Thank you for sharing and the video looks like it is running nice and smooth, congrats on a job well done!

Hmm not so much. That video was before (among many) the hook repair. I'm going to try and get video of it now - same circumstances, before I drop an 85HP on it. The difference is remarkable.

 

[GT1000000]

Re: Hull Hook Repair

Hmm not so much. That video was before (among many) the hook repair. I'm going to try and get video of it now - same circumstances, before I drop an 85HP on it. The difference is remarkable.

Oh OK, I misread... I thought that was the AFTER video, not the BEFORE...
Can't wait to see the After Video, hopefully it shows the difference...

 

[Yesterday]

Re: Hull Hook Repair

Oh OK, I misread... I thought that was the AFTER video, not the BEFORE...
Can't wait to see the After Video, hopefully it shows the difference...

You can count on it!! Now it just has to stay warm enough to repeat the test!