Fiberglass hull flex

[Nate W]

I have a 1989 Procraft 1780V fish or ski boat. When I bought this boat it had a small (1/2"x1" wide and about 1/4" deep) chip in the bottom of the hull on the front port side. I cut the bottom of the storage area out to get the to hull and repair the chip fron the inside.I preped the area about 1'x1' and put new fiberglass over the chip fron the inside. I took the boat out this weekend and had someone watch the "fix" when I hit waves and they said it flexed about 1/2" when I would hit a wave. Is it normal for a boat to flex this much? The boat also pulls hard to the starboard side (no trim tap at all) is that normal? Thanks for the help.

 

[Gary H NC]

Re: Fiberglass hull flex

I think all boats will flex to a certain point but that sounds like a lot.
Have you checked the stringers for rot?
Rotten stringers will let the hull flex much more than its supposed to.
They are the back bone of the hull.

On the pulling,Are you saying there is no tab to adjust above the prop?

 

[Nate W]

Re: Fiberglass hull flex

I think all boats will flex to a certain point but that sounds like a lot.
Have you checked the stringers for rot?
Rotten stringers will let the hull flex much more than its supposed to.
They are the back bone of the hull.

On the pulling,Are you saying there is no tab to adjust above the prop?

I really didn't see any stringers in the area in question. Maybe I should drop this boat of to a pro and have them take a look.

That is correct there is no tab above the prop to adjust.

 

[oops!]

Re: Fiberglass hull flex

its allmost impossible to determine the rate of flex in a moving boat.....

the big thing about the repair....is that there was no water coming in !!!!.

you were putting a patch on the hull.....now...if you were stiffening the hull thats a different story.......


a lot of boats in the late 80's early 90's,were ....uhhh....welll.....mass produced......it was the more, faster, cheaper, era of boat building. a really bad time for quality. (some of the manufacturers stuck to their guns and still made a quality craft).

during this time.....a lot of manns used foam to give the hull rigidity, actually im shocked that you can get into the hull with out going thru foam. is the repair area in the ski locker?

if the repair area is the only portion of the hull that is flexing, and its really worring you......cut a 1 foot squair peice of fabric called 1708 bi ax.
cover the repair area....(after roughing the area and cleaning with aceitone).
that will give you more than enough stiffness.
it will still flex, but it will give you the peace of mind you are looking for.

(if you are wondering, how strong the fiberglass is....in an hour or two hour i will be posting a fiberglass stregnth and stiffness test on the "hull extension in progress" thread in the restoration section)

cheers
oops

 

[Gary H NC]

Re: Fiberglass hull flex

On the trim tab post what year and model engine you have and we can find you a part number for it.
It really needs one to correct torque steer.

 

[Nate W]

Re: Fiberglass hull flex

its allmost impossible to determine the rate of flex in a moving boat.....

the big thing about the repair....is that there was no water coming in !!!!.

you were putting a patch on the hull.....now...if you were stiffening the hull thats a different story.......


a lot of boats in the late 80's early 90's,were ....uhhh....welll.....mass produced......it was the more, faster, cheaper, era of boat building. a really bad time for quality. (some of the manufacturers stuck to their guns and still made a quality craft).

during this time.....a lot of manns used foam to give the hull rigidity, actually im shocked that you can get into the hull with out going thru foam. is the repair area in the ski locker?

if the repair area is the only portion of the hull that is flexing, and its really worring you......cut a 1 foot squair peice of fabric called 1708 bi ax.
cover the repair area....(after roughing the area and cleaning with aceitone).
that will give you more than enough stiffness.
it will still flex, but it will give you the peace of mind you are looking for.

(if you are wondering, how strong the fiberglass is....in an hour or two hour i will be posting a fiberglass stregnth and stiffness test on the "hull extension in progress" thread in the restoration section)

cheers
oops

The repair is not in the ski locker but under the front storage area on the port side.I didn't have to remove any foam but I did have to cut out the floor in the storage area (wood and glass).

The motor is a 1987 150 Merc XR2. Is it mormal to have this torque steer without a trim tap?


Thanks for all the help guys as you can tell I'm a FNG to all this.I just don't want my boat to break in half

 

[Gary H NC]

Re: Fiberglass hull flex

The Merc parts list comes up with this one for the trim tab...anode,
And yes,without one can cause the steering problems.
http://www.go2marine.com/product.do?no=42089F

 

[Nate W]

Re: Fiberglass hull flex

The Merc parts list comes up with this one for the trim tab...anode,
And yes,without one can cause the steering problems.
http://www.go2marine.com/product.do?no=42089F

Thank you for the link and info.

I'm taking my boat to a marina tomorrow to have them look at the hull.I'll try to post some pics of it when I get back.