Boating How-To’s : The Kerno Memorial Forum - repairing/replacing soggy runabout floor

THE HULL TRUTH is the world's largest FREE network for the discussion of Boating & Fishing. Whether you're researching a new boat, or are a seasoned Captain, you'll find The Hull Truth Boating & Fishing Message Forum contains a wealth of information from Boaters and Sportfishermen around the world.




Larson170
03-29-2012, 07:22 PM
I bought a used 20 year old Larson Runabout last year with a soft floor in the rear. I ran it until the end of the summer, tiptoeing around. Now after pulling up the carpet and the section of “replacement deck” installed by the prior owner, I was able to more clearly see the extent of the wood rot which is still mostly confined to the back end of the boat that were covered in carpet (mostly in the middle around the gas tank).
The stringers (the two long pieces that run the length of the boat?) appear to be 2” wide solid wood beamlike and are black and rotten for about three feet from the back of the boat and 2-4 inches down. The bulkheads which I take to be the sections running the width of the boat are plywood with some sort of coating (fiberglass?) and look to be in better shape except for where they cross the middle. There are solid foam blocks underneath the parts of the deck which I can only partially glimpse as they are still under what’s left of the deck on either side of the stringer to the sides of the boat.
My thoughts are that I could cut back the stringers to get to the good wood, patch on another piece of solid wood, then put another deck on top of what’s left of the old deck, and put down new carpet. However marine grade plywood is not readily available where I live in rural Northern NY as far as I know. And I am not sure what else I should do to it before putting on the carpet.
I’ve tried to read the posts here, but I am confused by the different terminology used. Some say they have used Plywood coated with epoxy. Others say plywood, fiberglass matt, and epoxy. Another mentions something called Coosa.
What are they talking about and where do you get this stuff? Am I safe to assume that when mentioning plywood that they always mean marine grade plywood? And am I crazy to even think about doing this on my own?


seaeagle2
03-30-2012, 08:44 AM
There's a book called "Runabout Renovation" that walks you through how to do what you want to do. As far as marine grade plywood, the original plywood in your boat was probably what ever was the cheapest.... High quality foreign marine plywood uses thinner plys so there's more plys, domestic marine plywood means they plugged the knot holes and there's not supposed to be voids in the interior plys. Same glue as exterior grade plywood. For a boat deck you'd be fine with good exterior (NOT CDX).
Be sure to get a respirater and tyvec suit.... I did a 17 runabout, its something you'll do once.....

Larson170
03-30-2012, 02:45 PM
I read that book, but no longer have it. It's almost as old as my boat. Has nothing changed in boat renovations sine then?
I remember him mentioning the "glassing" process but don't recall him saying anything about epoxy that the other forum members are mentioning. Do I need the "glassing"?
Aside from the plywood, where do I get the other stuff I need. Is there a good catch-all resource online, or can I find this at Home Depot, Lowes or local hardware store?
And this is probably a dumb question, but what's the tyvec suit and respirator for?


seaeagle2
03-30-2012, 03:38 PM
And this is probably a dumb question, but what's the tyvec suit and respirator for?
If you're going to be using polyester resin or epoxy resin in the quantities you'll need to do a repair, you should use a respirator and when you're going to do as much sanding / grinding as you'll have to, you can get "dust mask" pads for the respirator, and the suit will keep you from getting the itchies. Afterall, you're going to be making a lot of very fine glass particles, not what you want in your lungs. Sure you can do it with out proper protective gear, but as they always say in the safety meetings, "what's a lung worth?"

Larson170
04-01-2012, 05:42 PM
Here are some pics of the problem area.

LouC
04-02-2012, 07:07 PM
Go over to
www.iboats.com
look in the boat restoration forum, it's one of the best around. This is a nasty itchy job, make sure the boat is worth it to you before committing to it. It can be done but takes time and you need to make sure you take precautions--tyvec suit, goggles, gloves, respirator, for fumes and fiberglass dust if grinding. Fiberglass dust is VERY bad for your lungs and eyes so be careful.

cmw
04-02-2012, 08:08 PM
im not an expert but i have done a few decks in the last 5 years. First you can find all the fibr glass products at west marine or hamilton marine. both can be found online. if you are going to keep the boat i would spend the money and use coosa board. i know a lot of people bicker about the cost, but if you plan to keep the boat for 10 years or so its worth it . you will never need to repace it ever. it is like plywood only made of foam and fiberglass mixed to put it simply. it is way lighter than wood and is just as easy to work with. you can also research them online. i have rebuilt 2 boat decks with it and i am getting ready to do 2 more soon.after using it the first time i swore its all i would ever use again. if not sure how long u want to keep it use good plywood. i recomend using polyester resin instead of apoxy resin because for what you are using it fore its not worth all the exra expence ( i know, but ill spend it on the coosa), if you need more than 2 gallons its usualy more cost efective to buy a 5 gallon bucket. when people talk about fiberglassing they are refering to putting resin over fiberglass material onto wood or whatever you are fixing. hope this helps some.

Larson170
04-03-2012, 05:07 PM
Coosa might be the way to go, if it's easier. I'm not so sure I want to get into all the fiberglass mess. I am not trying to make the boat look like new again. I'd like to get 5-6 years out of it and have a floor that I can walk on.

Larson170
04-05-2012, 04:34 PM
im not an expert but i have done a few decks in the last 5 years. First you can find all the fibr glass products at west marine or hamilton marine. both can be found online. if you are going to keep the boat i would spend the money and use coosa board. i know a lot of people bicker about the cost, but if you plan to keep the boat for 10 years or so its worth it . you will never need to repace it ever. it is like plywood only made of foam and fiberglass mixed to put it simply. it is way lighter than wood and is just as easy to work with. you can also research them online. i have rebuilt 2 boat decks with it and i am getting ready to do 2 more soon.after using it the first time i swore its all i would ever use again. if not sure how long u want to keep it use good plywood. i recomend using polyester resin instead of apoxy resin because for what you are using it fore its not worth all the exra expence ( i know, but ill spend it on the coosa), if you need more than 2 gallons its usualy more cost efective to buy a 5 gallon bucket. when people talk about fiberglassing they are refering to putting resin over fiberglass material onto wood or whatever you are fixing. hope this helps some.

If I use Coosa board for the deck can I skip the resin/fiberglass process? Bluwater 20 is going to run almost $500 for 2 1/2 inch boards shipped.

cmw
04-07-2012, 02:49 PM
hey larson 170,sorry ive been to buisy to get to the computer. yes if you buy the blue water 26, depending on how wide a span you are covering you will not have to get crazy with fiberglass. what i have done in the past is put a heavy coat of resin on bouth sides of the coosa, it is sort of poris as it comes. you will need to paint or cover with a carpet when done because niether the coosa or the resin is uv stable and it will brake down in the sun if not protected. if the span is so large that the board bows under wieght, you will have to iether put some supports undernieth it or add a couple layers of resin and fiberglass cloth. i cant remember off the top of my head what the maximum span u can use with the blue water 26 ( check on coosas web sight, if not i can check with my rep). im not sure if you had mentioned what the span you are covering is. i have done this on several john boat raised casting deck conversoins. i wish i was computer savy enough to post the pictuers i took from start to finish on the last one i did. i hope this helps and doesnt confuse you .

Larson170
04-07-2012, 04:07 PM
My thought is that I could place the two boards side by side perpendicular to the centerline of the boat and cover it with carpet. The width of the boat is such that the a single board can be trimmed to fit against the curved sides of the boat.

Marky mark
04-07-2012, 07:06 PM
Hi Larson,

Hate to be the bearer of bad news but I think there is a bit more to be done with your hull than just replacing the deck. When you have the sort of rot you have in your stringers (as you say the longitudinal structural beams) the hull is potentially compromised and could fail. There needs to be more than just a new floor on this sucker I suspect. A real fix involves pulling out the motor, fuel tank, plumbing etc etc, cutting out the old structure (stringers, bulkheads) and grinding the old fibreglass back to get a good adhesion. Then installing a new sub frame and then floor on top. The question of what materials comes down to a bit of cost benefit analysis. Ply wood is the cheapest option for structure, when soaked in thinned resin then fibreglassed into the hull using a mixture of resin and fibreglass woven cloth will last quite a long time, in some cases 20 years plus. Composite structures like penske or coosa board replace the plywood with something that won't rot ever but are more expensive. Even so they will need to be fibreglassed into the structure with resin and cloth to work. Then there is the choice of resins, polyester resin is cheap, reasonably toxic (good quality respirator, gloves, suit etc) and used in the majority of boat builds. It doesn't have the best adhesion to the existing hull but has been used successfully in many renovations before and no doubt again. Epoxy resin will offer better adhesion, be less dangerous during use but cost a heap more.

If you take this sucker on properly it will be a lot of work, you'll need a clean work space and cost a fair bit. If you really like your engine and hull and have the time to spare go for it, otherwise scrap the beast, try and get some cash for the engine, parts, trailer, electronics etc etc and replace it with a more sound hull. Third option is spend a bit, glass in a new dodgy floor (ply is cheapest, soak it in resin it'll last a lot longer than the rest of the sub floor by the looks of things!) and try your luck, it may last a while, it may not.

Only you can make that decision, good luck!

Big Island Lifer
04-07-2012, 07:42 PM
Your safety and the safety of your family and friends depends on a safe vessel. It sounds like you want to cut every corner possible, but that just isn't a good idea. If you don't want to repair this boat sell it for scrap and look for another. Don't fool yourself with a patch job only to endanger yourself later.

Larson170
04-08-2012, 07:12 PM
...I think there is a bit more to be done with your hull than just replacing the deck. When you have the sort of rot you have in your stringers (as you say the longitudinal structural beams) the hull is potentially compromised and could fail. There needs to be more than just a new floor on this sucker I suspect. A real fix involves pulling out the motor, fuel tank, plumbing etc etc, cutting out the old structure (stringers, bulkheads) and grinding the old fibreglass back to get a good adhesion. Then installing a new sub frame and then floor on top.

Those are some sobering words. Do we really need to take out all the subframe down to the hull? I thought I read somewhere that you could cut back the stringer to below the rot line and then add in new support.

I can't afford a new "used" boat and don't have the time, patience or skill to take on a project of that magnitude.I guess I was just kidding myself. But I need a boat, even if it means I have to sink more money into it. Dumb questions- Any guesses on what a run-of-the-mill marina would charge to do this right with plywood? Or what's a 20 year old 115 hp 3L Mercruiser I/O motor going for?

poqfishin13
04-09-2012, 01:05 PM
Those are some sobering words. Do we really need to take out all the subframe down to the hull? I thought I read somewhere that you could cut back the stringer to below the rot line and then add in new support.

I can't afford a new "used" boat and don't have the time, patience or skill to take on a project of that magnitude.I guess I was just kidding myself. But I need a boat, even if it means I have to sink more money into it. Dumb questions- Any guesses on what a run-of-the-mill marina would charge to do this right with plywood? Or what's a 20 year old 115 hp 3L Mercruiser I/O motor going for?

i agree with what they said. although right now you may not have the problems. it would be in your best interest to cut the whole floor out. remove the engine fuel tank and everything. then see the extent of the damage you have and start cutting. just make sure you brace the hull. once everything is out you get to put it all back together. which isnt so much skill its just more patience to get it all level and right than anything:thumbsup:

grodywhite
04-09-2012, 01:12 PM
I agree that it's really not terribly difficult but it is a lot of very dusty, itchy hours and will cost some dough.

You really need to decide if you like this boat before you start cutting. And that you'll figure on keeping it for a few years afterwards in order to get some good times out of it.

And while the floors and stringers aren't all that tough, the transom will likely take the bulk of your time. Better be sure to check that for rot as well.

Been there, done this. It's all too easy to spend more money and time than the boat could ever be worth.

LouC
04-09-2012, 04:23 PM
Been there and done that. Once was enough for me. I would say bit the bullet and fix this one, if you can't afford a newer boat with no rot. That's why I did mine, I did the demo, paid a shop to repair the rotted stringers, replaced the foam and installed the new deck myself. It's a LOT of work and toxic at that. You need the full protection of goggles, tyvec suit, particle and fume respirator, etc. Grinding fibreglass is very very bad for your lungs and eyes. DO NOT do this without protection.

My next boat will be a late model 3-5 years old max. I don't mind mechanical repairs, but fiberglass repairs, no thanks.

Looking at yours, that deck has to come out and the rotted stringers have to as well. Someone already tried to shore things up but tem fixes are just that, temporary good for a season or 2. Not safe in the long run.

go over to www.iboats.com and look in the boat restoration forum,. and see if you're up to it. Look at friscoboaters re-hab of a 95 Sea Ray, he did a great job with lots of pix and vids.

Larson170
04-18-2012, 07:10 PM
Update: We took out the gas tank and took back more of the deck. I was surprised to find that the foam covers every crevice under the deck with the obvious exclusion of the center channel. The foam is firm but not brittle. I also discovered that the piece that I labeled as solid wood stringer was just a support insert. It was not glassed. The stringer is all plywood glassed at the bottom but not at the top. Cutting it down about 3-4 inches reveals solid dry plywood. We took out a four foot section to that depth which leaves about 6 inches of the stringer to the bottom of the boat. The center bulkhead is in three parts. The middle section in front of the gas tank was also cut down to the solid wood. The back part of the boat that was not covered by carpet still seems very sound as does the front. I am going to order the West system epoxy resin and slow hardener, because it seems safer and more forgiving to use. the plan is to patch in the stringer with extra reinforcement and glass it all in and lay in the new deck on top of the existing foam and repaired stringer and glass that in.

Larson170
07-01-2012, 06:15 AM
Update (two months and a grand later): The boat is complete and back in the water with a ski pylon to boot. Thanks Dad. :grin:



Search Engine Friendly URLs by vBSEO 3.2.0