Fiberglass Repair with big patches? Or fill with CSM and resin?

[t-osu]

Hi all,

Acquired a free boat. It's got some eating away on the keel (not really a chip, not a hole), some spider cracks (I think they're called), and previous repairs of filled in spots...

I have done everything imaginable to drive trains, steering, motors, but I absolutely have NO experience on body work! So, I'm looking for some advice on what best to do. I've watched a lot of videos and some people go the CSM and resin gelcoat route and some folks take a grinder to it and a massive hole appears that needs to be patched with large pieces of fiberglass.
I would feel comfortable doing the former, definitely not the latter.

I've attached some photos of what I'm dealing with; they have labels I hope are slightly helpful.
Thanks for the advice and tips! Hope it's not too bad...

 

[Scott Danforth]

Before you worry about cosmetic issues....ask yoursef....is the transom and stringer wood sound, or rotted?

Free boats are the most expensive because they need the most work

 

[t-osu]

Before you worry about cosmetic issues....ask yoursef....is the transom and stringer wood sound, or rotted?

Free boats are the most expensive because they need the most work

Appreciate it! I'm not too worried because it was a boat from my friend. He often buys things and doesn't know how to finish them so I get to acquire them when he moves on to some other poor project :]

Yes, I checked stringers by walking around on it and jumping VERY slightly, trying to test and feel for any sags, but it was solid. For the transom I tilted it up and pushed down on the lower unit repeatedly so it was sort of bouncing to see if there was any give in the transom, but it was solid, too.
Removed the engine cover and checked all the wires, they broke apart so I re-wired it, took about a day.
Removed and cleaned the carbs, but they looked fine.
Removed the lower drain plugs to check the gear oil for water contamination. Had to rebuild the lower unit for oil seals and while I was at it, did the water pump and checked other gaskets/o-rings, ~$100

It runs great, actually (I use a tub and took it out on a lake a couple times). Those body-repair areas are bugging me though and I want to make sure I deal with them if I need to before they progress into something really bad. If there are other tests I should look for that I've overlooked and are more serious before starting this body work, please do tell!

 

[todhunter]

Your stringer and transom tests are not accurate ways of detecting rot unless we are talking complete rot to where the wood is completely gone to a liquid state. You need to drill test holes near the bottom of the stringers and transom and look at / smell what comes out. Light colored saw dust that smells fresh is good. Anything liquid, black, stinky, damp, or dark colored means you have wet rotten wood that needs to be replaced. If your drill test passes, you can plug the holes with your favorite marine sealant and go boating.

 

[Scott Danforth]

dont use a tub to run an outdrive in it unless you want to toast your impeller. you need to use muffs

you cant tell rot by jumping very lightly. you have to make test drills

 

[t-osu]

Your stringer and transom tests are not accurate ways of detecting rot unless we are talking complete rot to where the wood is completely gone to a liquid state. You need to drill test holes near the bottom of the stringers and transom and look at / smell what comes out. Light colored saw dust that smells fresh is good. Anything liquid, black, stinky, damp, or dark colored means you have wet rotten wood that needs to be replaced. If your drill test passes, you can plug the holes with your favorite marine sealant and go boating.

Guess I didn't dive deep enough into online videos, appreciate it! I'll go ahead and do that today.
When you say I can "plug the holes...and go boating", does that mean if my stringers/transom pass, you believe my original post (about the eating away on the keel) doesn't need to be addressed?

 

[t-osu]

dont use a tub to run an outdrive in it unless you want to toast your impeller. you need to use muffs

you cant tell rot by jumping very lightly. you have to make test drills

Ah OK. I feel like I've heard different things. I thought that running in a tub helped emulate the forces it would feel as if operating actually in the water, but I'll go ahead and order some. Thanks!

 

[Scott Danforth]

Ah OK. I feel like I've heard different things. I thought that running in a tub helped emulate the forces it would feel as if operating actually in the water, but I'll go ahead and order some. Thanks!

if the tub is big enough to have the whole outdrive in the water, then yes.

if you attempted to pull water from a tub, you just smoked your impeller. impellers do not pull water, they only push. so they have to be below the water when you start to prime.

 

[buxmj]

Definitely find out about the structural integrity of the inside of the boat first. It does look like the exterior is cosmetic from what I see. Not worth it to spend time and money on that and then find out you are pushing a soaked sponge around the waterways. Good luck and keep us posted.

 

[todhunter]

When you say I can "plug the holes...and go boating", does that mean if my stringers/transom pass, you believe my original post (about the eating away on the keel) doesn't need to be addressed?

I would still fix the keel first. I had similar damage and softened the jagged edges with a dremel, filled with thickened gelcoat, then applied gelcoat over a larger area. It doesn't look the best since I didn't color match the gelcoat or do any fairing, but I'm putting a KeelShield over it. See here.

 

[t-osu]

if the tub is big enough to have the whole outdrive in the water, then yes.

if you attempted to pull water from a tub, you just smoked your impeller. impellers do not pull water, they only push. so they have to be below the water when you start to prime.

Oh yeah, for sure! I always make sure the water line is above basically my whole lower unit. It's a 50 gallon tub, supposed to be for my wifes gardening...but I've been "borrowing" it haha.

 

[JASinIL2006]

If you look at how much of an outdrive is submerged, even when the boat is on plane, you'll see that it's really not possible to run the drive in a bucket. You need the muffs to force water into the intakes.

 

[Scott Danforth]

Oh yeah, for sure! I always make sure the water line is above basically my whole lower unit. It's a 50 gallon tub, supposed to be for my wifes gardening...but I've been "borrowing" it haha.

not just the lower unit. you need water 7" above the impeller. that is usually the whole drive under water.

as in a 10,000 gallon tub

then when you are on plane, the forward momentum helps push water up the intake

 

[t-osu]

not just the lower unit. you need water 7" above the impeller. that is usually the whole drive under water.

as in a 10,000 gallon tub

then when you are on plane, the forward momentum helps push water up the intake

Gotcha, good to know. I've used muffs in the past with my dad, but when I acquired this boat and did some reading online there seemed to be a divide between folks who love/hate muffs and then reasons to prefer tubs. I'll switch back to the muffs :]

Also, overall update. I drilled 5 holes in the transom in various places. All came out looking exactly the same. Light brown and when I blew on it, it flew away! Smelled good too. I also saw a hammer test for rapping on the transom and that all sounded pierced and sharp.

I think I lucked out! Good tests to know in the future when I buy my own used boat! Although I bet the seller won't let me drill holes into it XD

Thank you everyone! I'll likely follow the post from todhunter on fixing my keel.

 

[Scott Danforth]

Did you drill near the transom drain?

 

[t-osu]

Did you drill near the transom drain?

Yes! I made sure to include areas near existing holes/bolts. So the drain, motor mounts, there was a depth finder, and there's a trolling motor mount