Floor repair advice needed

[bluey]

Greetings,

The 19' F/glass boat I am restoring was originally manufactured with a foam filled f/glass floor along each side of the bilge. At some time, and for whatever reason, the original floor has been cut out and replaced with 3/4" Marine (?) Ply. This plywood floor is rotted along with most of the ribs underneath it (see photo 1.) and I am now in the process of removing all of the ribs and timber associated with it. The ribs underneath were also made of plywood and were installed to support the plywood floor, they were glued to the hull and were reinforced with fiberglass strips. (see photo 2.)

If you look at photo 3. you will see that the original fiberglass floor had V-shaped supporting ribs running across but they did not extend down to the hull. So I am thinking that it is not necessary to go to the trouble of fitting new ribs.

As I intend to replace the floor with 1/2 Marine Ply I am thinking of gluing some 2"x1" timber to the under side of the new it as a kind of supporting frame, then screwing and gluing the new floor assembly into place. This way the floor becomes self supporting and does not rely on the hull.

I am wondering what others would do in this situation? Do you think that this would be a strong enough flooring method or would it have too much flex?


1.

2.

3.

Cheers,
bluey.

 

[rickryder]

Re: Floor repair advice needed

Welcome to iboats! I would suggest to do a search for stringer and deck replacement.... That will give you so much information on your rebuild.

As far as redesigning your deck and stringers.... I would stick to what the engineers decided to put there in the first place. All I would do is do a better job at the fiberglass work....seems the boat builders just slap them together cheap for a bigger profit margin.

 

[oops!]

Re: Floor repair advice needed

yeah....rule of thumb is to replace what was there.....but this time...glass the underside of the deck with waxed resin...it will last for years with minimal care.

there is a deck replacement in the link in my sig

cheers
oops

 

[drewpster]

Re: Floor repair advice needed

Bare in mind that the stringers (longitudinal timbers), the bulkheads (diagonal trusses), and wings (triangles outside stringers), are not only there the support the deck, they are there to support the hull skin under them. Whatever system you re-install should give the same support to the hull and the deck or flexing can occur. The deck and hull are meant to tie together as an integral structure.
The fiberglass strips (tabbing) are meant to bond these pieces to the deck. Unfortunately, like most all restorers find, yours were installed poorly with inadequate fiberglass work to keep water out of them. They got soaked, stayed wet and eventually rotted. So anything you replace them with should be covered in enough fiberglass to keep them water sound and bonded to the deck.

example

 

[tschmidty]

Re: Floor repair advice needed

Yeah, I'll third the advice to replace the horizontal stringers. Your hull doesn't have a lot to support that skin, there are no chines to stiffen it from front to back. So it will certainly flex, and if nothing else would most likely be loud. I'd also replace the foam that was there with something at least.

Your idea to replace the v shaped ribs with pieces underneath the plywood is fine.

 

[rickryder]

Re: Floor repair advice needed

I'd also replace the foam that was there with something at least.

I was under the assumption that all boats under 21' need to have flotation foam by USCG rules/regs.



FEDERAL LAW:
183.201 Applicability.
(a) This subpart applies to monohull outboard boats that are:
(1) Less than 20 feet in length; and
(2) Rated for outboard engines of more than 2 horsepower.
(b) This subpart does not apply to sailboats, canoes, kayaks, inflatable boats,
submersibles, surface effect vessels, amphibious vessels, and raceboats.
Discussion:
Monohull boats under 20 feet in length and rated for more than two horsepower must comply with
the more sophisticated flotation system called Level Flotation. The Level Flotation system requires
that the swamped boat, loaded with certain weights representing weight capacity, part of persons
capacity and some equipment, must float in an approximately level position and not heel past a
certain angle, even when part of the passengers? weight is on one side of the passenger carrying
area. Section 5.0 covers the requirements and tests to perform.

 

[idonthaveaname]

Re: Floor repair advice needed

I was under the assumption that all boats under 21' need to have flotation foam by USCG rules/regs.

I think that's for new boats, not that one should treat a restore any differently.

 

[Bondo]

Re: Floor repair advice needed

I was under the assumption that all boats under 21' need to have flotation foam by USCG rules/regs.



FEDERAL LAW:
183.201 Applicability.
(a) This subpart applies to monohull outboard boats that are:
(1) Less than 20 feet in length; and
(2) Rated for outboard engines of more than 2 horsepower.
(b) This subpart does not apply to sailboats, canoes, kayaks, inflatable boats,
submersibles, surface effect vessels, amphibious vessels, and raceboats.
Discussion:
Monohull boats under 20 feet in length and rated for more than two horsepower must comply with
the more sophisticated flotation system called Level Flotation. The Level Flotation system requires
that the swamped boat, loaded with certain weights representing weight capacity, part of persons
capacity and some equipment, must float in an approximately level position and not heel past a
certain angle, even when part of the passengers? weight is on one side of the passenger carrying
area. Section 5.0 covers the requirements and tests to perform.

Ayuh,... That's for OEManufacturers....

Your boat, is Your boat, 'n that doesn't apply....

 

[rickryder]

Re: Floor repair advice needed

That edit post was from the USCG Boatbuilders handbook.

 

[rickryder]

Re: Floor repair advice needed

Ahhh ok thanks Bond-o I thought it was a law..... I know I will be putting foam back in mine.... I'm not going to put lots of hours of work and money into a boat and chance it ever sinking to the bottom!

 

[bluey]

Re: Floor repair advice needed

"I was under the assumption that all boats under 21' need to have flotation foam by USCG rules/regs."

USCG rules/regs don't apply to us here in Australia.

Thanks for the replies to my query and the good advice. I should add that this boat is a solid fibreglass one. Apart from the engine bearers there is no wood other used in the construction. The hull is 3/8" thick and the keel and stringers are all F/glass, the keel itself is around 8" at it's widest point and the gunwhale is foam cored. It is a solid fishing boat powered by a 2 cylinder 2QM15 Yanmar diesel and does about 8 knots. Most of the reinforcing is with foam cored f/glass and this is what the floor and it's supporting ribs was originally constructed of. Restoring the floor to it's original specs is beyond my ability and financial capacity so I will have to be satisfied with a new plywood floor but all nicely sealed and encapsulated of course. I will be sure to take your advice and reinforced the hull where necessary. Thanks again to everyone for the help.

Cheers,
bluey in Oz.

 

[tschmidty]

Re: Floor repair advice needed

Interesting. So someone tore out the original supporting bits that were foam and fiberglass and replaced with wood? That will work but a little surprising the originals need to be replaced unless they damaged it tearing out the floor in the first place.

If you are going offshore I would say the foam is an absolute requirement, I am sure australia has similar guidelines. You can save a few bucks by buying some sheets of insulated foam and then just encapsulating that with some of the urethane expanding closed cell foam. Definitely worth doing.

 

[bluey]

Re: Floor repair advice needed

........You can save a few bucks by buying some sheets of insulated foam and then just encapsulating that with some of the urethane expanding closed cell foam. Definitely worth doing.

Hi tschmidty,

Insulated foam is something I had not thought of. Sounds like a good idea, I'll check it out, thanks.

bluey.