Help! Help! Help! Deformed hull on trailer!

[AJSVFORCE]

I am ready to start glassing in my stringers but when i put them in for checking measurements one side is way off!
I have since found out that the trailer the boat is sitting on is not the trailer the boat came with when it was purchased!Some of the bunks are only touching the hull on one end and the two middle rollers that the keel rides on dont even touch the keel!
How do you know where the bunks are supposed to contact the hull and how do i know when any of my measurements are correct when the hull has flexed from its normal form?
I have tried to adjust the bunks and rollers and the huge nuts wont budge,or the whole stud turns and tears up the bunks.
Is there any way of finding out when the hull is at its normal form before it flexed?

Please help!
Thanks for your time,
Andy

 

[erikgreen]

Re: Help! Help! Help!

Re: Help! Help! Help!

Okay, first... try to put a useful title on your messages, something like "Hull warped on trailer... how do I make it true?"

Second, relax. This has happened to other people.

To do significant stringer work on a hull you should support it on a bunk trailer or stands, since both of these will support the hull pretty well. Since you didn't do this (as recommended in other posts here regarding hull support) you get to fix a warped hull.

You can check if it's square in one plane by attaching a string to a point on the centerline, either at the bow or in the middle of the boat behind the windshield. Use string that won't stretch too much. Pull the string to one of the aft corners of the boat and make a mark on the string where it's even with the corner.

Pull the string to the other corner and you should be able to see how much distortion the hull has by comparing the mark on the string to the corner. At that point you need to raise or lower the two rearmost hull corners until the distance from them to the origin of the string is the same. This will untwist the hull.

This works for hulls that have "oilcanned" or twisted, which is usually how an unsupported hull distorts on a trailer (you can also get hooks, or dents, near the individual rollers). If your hull has bent significantly to one side or vertically you'll have to detect and correct that in another way, but this will get you started.

Erik

PS: You have to make sure the hull is properly supported before you do this, of course.

 

[AJSVFORCE]

Re: Help! Help! Help!

Re: Help! Help! Help!

Thank you for the reply,i was starting to think no one was going to.
First let me explain my situation so you can grasp the entire screwup and hopefully help me fix it.
First,the Cap is still intact on the boat,I know you should remove it but i have no way to do it,and i dont want to try to fix all the spiderwebs that are sure to appear if i got it off without destroying it all together.
Second,the motor is still in the boat as well,yes I know,not supposed to leave it in and the reasons dont really matter,this is where i am in my rebuild.
There is zero wood left in the hull of the boat.The motor is supported in a way so i can replace all the stringers and deck of the boat and not hurt the transom in any way.
The boat is a 21'Donzi Regazza Bowrider,the entire bow area is a part of the Cap and is fiberglass.The window on the bow will not close and overlaps about an inch at the top,i suspect this is because of the unsupported weight of the bow area itself.
I set the rear portion of the main stringers in place alongside the motor then put a piece of plywood "DECK" across them for measurement checking and fitting.Then i took measurements at both sides of the boat where the old deck line is still visable.One side was almost perfect the other was almost 11/2 inches low. This is where I Freaked Out and started checking my stringers and so on and so on.One stringer had a 1/4 inch gap from the hull to the bottom of the stringer directly in the middle of the stringer,only the two ends of the board were touching the hull.
If i shake the boat,you can see exactly where the bunks contact the hull as it flexes back and forth.
I just dont know what to do to get the hull back to its original shape,drop the center,raise the center??????
I need any help you can give,and thanks.

 

[AJSVFORCE]

Re: Help! Help! Help! Deformed hull on trailer!

Anyone???

 

[jonesg]

Re: Help! Help! Help! Deformed hull on trailer!

I have tried to adjust the bunks and rollers and the huge nuts wont budge,or the whole stud turns and tears up the bunks.
Andy

Cut them off, get an angle grinder and diamond steel disk, $30 for a cheap ryobi and $16 for the disk, that will cut the U brackets like butter.
I would jack the stern up a bit with a wooden block under the keel.
You might find the weight of the engine without the stringers is the problem anyway.

Buy new U brackets or whatever hardware you cut and start adjusting.
You might consider converting the rollers to bunk too....or place wooden shims across the rollers to spread the load.
An elec impact driver makes easy work of adjusting trailer bolts,
"easy" being a relative term.:redface:

 

[erikgreen]

Re: Help! Help! Help! Deformed hull on trailer!

Okay, sounds like you've got quite an issue. As you know, removing the wood structure from a hull is like removing all the bones from your body. It looks about the same, but it's free to collapse into a pile of mush.

We can't just tell you what to move to fix the problem because we're not there... it's not as simple as just saying "move X up by Y inches" because the way your hull is warped is probably very specific to your boat and the way it sits on your trailer.

Here's what I'd recommend to fix it:

1. Get the engine either out of the boat or suspended from overhead, so the weight isn't sitting on the hull or trailer. Likewise I'd try to remove as much weight from the cap as possible... windows, hardware, etc. It's all that weight pushing down on the hull that's making it flex.
2. Get a set of 5 jack stands or blocks that can hold your hull up
3. Lift the boat hull using a bottle jack or the tongue jack method (described elsewhere on this board) onto the jack stands:
4. Jack stand placement: One at each stern corner, one on the keel as far forward as possible (where it becomes horizontal as it goes aft) and two on the chine where the hull bottom meets the side (one port, one starboard) halfway between the stern stands and the one on the keel. This is a total of five points of support.
5. Check that none of the boat is resting on the trailer at all

Hopefully this should support the hull well enough that it will straighten itself somewhat. Fiberglass has a certain amount of stiffness, but it's heavy, and with the weight of the engine, cap, and topside stuff on it the whole hull will, as you know, flex some.

Supporting the hull this way, with five points of support, will "encourage" most small power boat hulls to "remember" their original shape, like when they were pulled from the mold.

But to be sure there aren't any warped panels or hooks left in the hull, you'll have to check it all over with mason's string and a straightedge.

Once it's the right shape, get the stringers and wood back in.

Erik

 

[salty87]

Re: Help! Help! Help! Deformed hull on trailer!

pictures would get you some more specific help.

are you in a garage? can you rig something to support the dash/bow area from above?...rafters or a-frame of some sort?

 

[AJSVFORCE]

Re: Help! Help! Help! Deformed hull on trailer!

It is sitting in my driveway and i have no way of removing the engine or cap. I did jack the boat up at the keel with a floor jack and wood. I then took a sledge hammer and beat the outer bunks as far outward as they would go. Then straightened them along with the inner bunks also.
The rollers at the center i cant adjust at all. The hull does not seem to be twisted,this Donzi is one heavy boat. I have lifted the sides of the boat and placed 4x4 wood blocks under the side between the hull and trailer fenders,this seems to help but i dont think there is any way i can get it back to the way the factory had it.
My question is,will the hull or deck or stringers fail or break if its not rebuilt in the factory specs form or shape?
Thanks,
Andy

 

[jonesg]

Re: Help! Help! Help! Deformed hull on trailer!

if its stressed and you glass stringers in it might ride strange and the cap might start cracking.

I would do whatever it takes so the stringers that are original copies fit like the old ones did.

If it took me a year I'd still do it and get it right before glassing anything back in.

Try as Erik suggests with string,
then...if the stringers fit and stringlines don't show any twisting , you got it.

 

[AJSVFORCE]

Re: Help! Help! Help! Deformed hull on trailer!

The hull is not twisted. Where the hull sits on bunks it is slightly bulged from the weight and i think the sides of the boat are down about an inch.
If you took a paperplate with food on it and held it in the center only, you would get what i have just not as dramatic.