Deck Reinforcement

[jonbellamy]

Hey guys. I've been given the boat in the below picture from my Grandpa. I've spent the last couple of months (in the Evinrude/Johnson forum) tuning up the engine (1968 Evinrude Fastwin 18hp). The boat is a "1979 14ft homemade fiberglass". As you can tell there isn't much to the boat. The boat floats well and hauls butt with the 18hp (the boat is light enough to throw). The transom seems sturdy and there are no holes in the boat.

I'm a decent sized guy, around 215 lbs, and the bottom of the boat bends a tiny bit when i stand up near the outer edges of the boat. I was just wondering if you guys had any ideas about adding some cushion to the floor so that it minimizes the bending. I thought about laying down some foam insulation and covering it with plywood, but was wondering if you guys think that could get water logged pretty easy? Any ideas would be appreciated. I'm not opposed to taking out one of the bench seats. Sorry I don't have any pics of the inside at the moment. If needed I can probably get some this weekend.

 

[bakerjw]

Re: Deck Reinforcement

I am no expert, but it sounds like the fiberglass might be a bit tired. I would expect that through the years that fatigue might have set in.

If it were me, I'd pull the bench seats and sand down the existing fiberglass to get a good bonding surface and then lay some new glass on top of what is already there. Myself, I'd avoid laying any plywood in there.

But that is just me. One of the regulars will likely be along with better advice.

 

[Woodonglass]

Re: Deck Reinforcement

Is this a Tinner or a Glass boat? Usually the seats in boats like this are needed to keep the sides of the hull from flexing. I would not remove them with out replacing with a casting deck or something. Pics of the inside would be a great help so we could see what you see.

 

[jonbellamy]

Re: Deck Reinforcement

Is this a Tinner or a Glass boat? Usually the seats in boats like this are needed to keep the sides of the hull from flexing. I would not remove them with out replacing with a casting deck or something. Pics of the inside would be a great help so we could see what you see.

This is a fiberglass boat (not really sure what tinner means, sorry). The seats do appear to keep the hull from flexing. I will get pictures hopefully this weekend (the boat is 30 mins from where i live).

I'm thinking about just laying down a layer of glass, seems easy enough and within my budget. To be honest, this boat has sat under that shed for the last 10-15 years. I'm not exaggerating that it hasn't run in at least 10 years and has probably been under the same shed for the same amount of time. I don't believe the hull has ever had water sitting in it, it's just that the hull is so thin i'm afraid my large self will eventually weaken it to the point where it becomes a danger for me.

 

[Woodonglass]

Re: Deck Reinforcement

Pics of the inside will be of great assistance. A "Tinner" is an acronym of an aluminum (Tin) boat.
If your inside hull is like I think then you might consider installing a 1/2" Plywood deck and tabbing to the sides of the hull and filling the void with the Blue Slab Foam from Lowes. Something like this...

 

[jonbellamy]

Re: Deck Reinforcement

Woodonglass, that was actually my initial thought. Excuse my ignorance, but what is CSM tabbing? New to boats and projects like these in general...

 

[jbcurt00]

Re: Deck Reinforcement

Tinner = aluminum boat. The 1st pix looks like it could have been tin/aluminum instead of fiberglass.

How are the seats & bench boxes attached to the hull?

It was probably always a light weight hull, but if the fiberglass was left exposed to UV, not covered by gelcoat or paint, & kept well covered, UV may have degraded the glass.

Does your grandfather know what the boat was made of? If it's polyester resin, you have some choices for laminating new glass over the old. If it's vinyl-ester (I doubt it) or epoxy (possibly) you need to use the same type of resin: VE or epoxy, like on like.

If you can't ID the resin used, you'll probably be better off using epoxy. It bonds well to both of the other 2.

You will need to make sure you have a good bonding surface for any of the 3 resins. That may require a good rough & scuff from a grinder. Use all the required PPE, and be extremely careful if the hull is thin.

Doing this work on the inside of the hull will keep more of the work hidden, but be much more difficult to do working around the benches.

Working from the exterior may require more labor to remove whatever current exterior finish (gel or paint) 1st then starting to rough & scuff the hull in prep for new glass. Then you may want to fair & smooth the hull before painting it.

Fiberglass is somewhat flexible, was it strained (creaking or cacking sounds would be bad) when you stood in it or just flexing?

 

[jonbellamy]

Re: Deck Reinforcement

Unfortunately, I don't know the type of fiberglass. It was made in 1979 and bought second hand. To be honest, it wasn't creaking or making any noise and it didn't feel like it was in any danger of cracking. The whole boat itself is pretty flexible and without the motor light enough for me to toss 10 ft. The main reason I want to put a layer of glass down is to reassure myself. I did stand right on the edge where the hull bends up towards the gunnel; it really just gave in a tad, but it scared me.

 

[jbcurt00]

Re: Deck Reinforcement

Was the boat in the water when you stood at the transition from the bottom to the sides of the hull?

 

[jonbellamy]

Re: Deck Reinforcement

Yeah the boat was in the water--should have clarified.

 

[jonbellamy]

Re: Deck Reinforcement

I should also note that the title is a little misleading. The boat doesn't have a deck, it should be more like "hull reinforcement". I apologize if I have confused anyone.