Preventing or identifying rotten floors

[Arronh]

I recently had a fiberglass boat with a rotten floor. Are there any ways to tell if your fiberglass boat is holding some water before it rots out? The one that I have now(1978 mark Twain 170V) doesn’t have any soft spots and seems to be good. I’d like to make sure it doesn’t have any issues or to seal up any cracks if it has any. Thanks. I store it inside when not in use.

 

[cptbill]

Generally speaking all boats absorb moisture, they spend there life in water. The older(and I guess some newer ones)that are fiberglass encapsulated wood more so but other than noticing a soft spot and short of taking core samples it's going to be hard

 

[Scott Danforth]

much like cars having a design life of 180,000 miles, light bulbs having a design life of 1500 hours, and lawn mowers 7 years, your boat has a design life. its about 15 years for small run-abouts like your 42 year old Mark twain

that means they put enough effort into the boat to last 15 years prior to items needing major work such as interior, motor, drive, hull, etc. they are planned to die so the companies can make more boats.

that being said, if you have a completely dry interior structure and dry flotation foam, and you properly clean and maintain a boat by keeping it in the garage vs left out in the elements, it can last decades.

boats rot from the inside out. they get water in the bilge, and that water migrates places. most boats have poor fiberglassing on the inside, mainly because they were not meant to last..... this allows water inside the boat to make it into places its not supposed to. that water then gets trapped. unless it salt water or ionized water, the trapped water had bacteria and mold spores in it. that is what leads to rot.

so on your 42 year old boat, the only way to know if you have a problem or not is to do some test drills into the transom and the stringers (from the inside of the boat), about 1" above the floor. just thru the fiberglass and into the wood

take a 1/4" drill bit, tape off 1/2" from the tip (so you dont drill thru the hull).

drill into the stringers and transom in a few areas (specifically back by the drain, and in the bilge area) about every 6 inches, and about 1" from the hull

after you get thru the fiberglass, you will hit wood. if the wood shavings are light-colored, dry and smell like fresh cut wood, you are golden...... however if the wood shavings are wet, dark-colored and smell like mulch..... you have rot.

 

[Arronh]

Thanks a bunch. I put a transducer on the transom yesterday and the wood seemed look like normal wood, so that’s good.

 

[Old Ironmaker]

Test the transom by gently bouncing up and down on the outdrive. A good transom is fantastic, it still doesn't tell you if the boat has rot. If I was a betting man I would bet the farm that 41 yr. old boat has wood rot.

What pray tell is your budget?

 

[JimS123]

How to tell? Its not rocket science. Marine surveyors have moisture meters to analyze whether there is water in the hull or not. Rotten wood is wet, so it'll show up. In my Engineering business I had access to the same equipment and it worked like wonders.

How to prevent it? Also easy peasy, though many of us are not so inclined or just don't care. After all, the boat will be sold or replaced in a few years anyway.

When you get home from a day on the water, go in the bilge and dry it out. Oh, I know, its too much trouble. Then put the boat in the garage. Oh, I know, I can't because its full of junk. OK, so put a good water tight canvas cover on the boat that breathes, so you don't get mildew, and then make sure the boat stays dry.

Boats rot because they are kept wet. Then, when it freezes in the winter the wood swells and cracks, making next year's lack of maintenance make things even worse.

A fiberglass boat will last for decades with only a small amount of care.

The generally accepted "15 year life span" is really only BS. However, it does ring true because of the poor way we treat our investment.

 

[Arronh]

I’m gonna make some test holes later this week before I get too committed long term. When making those test holes, should I fill them in with silicone, epoxy, resin, nothing, other?

As is, it’s in good shape for what I need. I got all the gauges going, installed a new radio, usb chargers, and tuned up a few other things. I live in the country with a big shed, so it’ll be easy to keep it indoors.

If taken care of, will fiberglass age and get brittle, or does it hold up?

also, what’s a good way to go in the bilge and dry it out?

 

[Old Ironmaker]

Fill the test holes with 3M 5200. Even 3M 4800 with suffice. I think it's 4800, might be wrong. 1st time this evening. To help answer your questions, yes glass will get brittle and crack as it ages. At 42 years old it has passed it's "Best Before" date by almost 25 or more years. It's an old boat Man. As far as Scott's best before date scenario that all depends on how it is maintained. I have a buddy that buys a new truck every 5 years. He does not wash that truck or clean the interior during the time he owns it. Once the warranty has elapsed he changes the oil and filter if he remembers to .If there is a noise he closes the window and turns up the radio. I hope you didn't buy his 42 yr. old barge. Don't throw too many good Benjamins into it.

Not knowing the design of your bilge opening it's difficult to make an observation blind. On my O/B tin StarCraft I only have an 8" opening to access the bilge area. If I needed to dry it out I would stick a hair blower into it.

Photo's would be nice to see here.

 

[JimS123]

If taken care of, will fiberglass age and get brittle, or does it hold up?

also, what’s a good way to go in the bilge and dry it out?

The enemy of almost everything is sunlight. Those UV rays will deteriorate the resins used in fiberglass boats. OTOH, if kept indoors I really don't believe the hull will get brittle with age. Obviously, it will get used outside some times, but in the overall scheme of things its a really low percentage.

The main issue is don't get the boat wet in the first place. If you are into watersports, throw a towel on the floor when you get back in the boat. If it rains while you are out, turn on the bilge pump and pull the plug when you get home.

The pump should be in the lowest part of the bilge. Whatever is left can merely be removed with a sponge or towel. If you can't access the spot because the engine or something is in the way, tip the boat as high as possible and pull the plug.

We owned our last boat for 35 years and never once mopped it out. The drain plug was never once removed. The bilge was easily visible and the pump drew out all but maybe a quart. The few times we got hit by thunder storms the pump took care of the water and the heat of the engine dried out the rest on the way home.

 

[Scott Danforth]

If you clean them, wash them, dry them, maintain them, and garage keep them, they last for decades.

the average owner doesnt...... so they dont..... the typical boat owner buys a boat, runs it once in a while, and in 3-5 years sells it when things start to go wrong

 

[Arronh]

Thanks again. I can’t figure out how to upload my pics, so I’ll take a video and share a YouTube link next time I can. It seems solid, but I look forward to doing some core tests. Considering the age, it seems like it’s been stored inside most of its life. The seats are outdated but in good condition. The old mercury motor runs well too. I’ve put very little money into it and will hold off on spending more.

 

[H20Rat]

much like cars having a design life of 180,000 miles, light bulbs having a design life of 1500 hours, and lawn mowers 7 years, your boat has a design life. its about 15 years for small run-abouts like your 42 year old Mark twain

Geez what are you doing to get 7 years out of a lawn mower? Even when I was mowing commercially we could get 5 years out of a MTD built tractor, and 1 year of that was about the equivalent of 20 years of normal homeowner duty. Current tractors are 2003 and 2005, just sold my 1979 John Deere 314 snowblower.

 

[Scott Danforth]

You have to understand design life....... The average lawnmower will run 7 seasons with no maintenance as the average home owner couldnt change oil if they wanted. We would sent out fleets of mowers to employees to see when they die. The requirement was to simply use the mower, however not to do maintenance. We were getting between 9 and 10 years.

The commercial lawn equipment was designed for about 2800 hours per year, with a major overhaul at 5 years and replacement at 10 years

 

[Old Ironmaker]

Scott, send me one of those test mowers and snow attachments here up north. I guarantee I will never do any maintenance.

 

[JimS123]

When I was a kid we had a reel push mower - no motor, just armstrong power. When I started college Dad figured I wouldn't be around much any more so he bought a Craftsman power mower. 3.5 HP Techumseh engine and an aluminum deck. When he got too old to mow any more and hired a service to do it for him, he gave me the old Craftsman to use at our Camp.

The old Craftsman is a 1964 model and is currently in its 55th year of service.

 

[Scott Danforth]

Scott, send me one of those test mowers and snow attachments here up north. I guarantee I will never do any maintenance.

unfortunately, I no longer work in the outdoor power equipment arena.

 

[Scott Danforth]

When I was a kid we had a reel push mower - no motor, just armstrong power. When I started college Dad figured I wouldn't be around much any more so he bought a Craftsman power mower. 3.5 HP Techumseh engine and an aluminum deck. When he got too old to mow any more and hired a service to do it for him, he gave me the old Craftsman to use at our Camp.

The old Craftsman is a 1964 model and is currently in its 55th year of service.

Not arguing that there are exceptions. However I am surprised the aluminum deck is original considering the bad vibration of the old L-head Techumseh motors.

 

[Old Ironmaker]

When I was a kid we had a reel push mower - no motor, just armstrong power. When I started college Dad figured I wouldn't be around much any more so he bought a Craftsman power mower.

The old Craftsman is a 1964 model and is currently in its 55th year of service.

My Dad built an electric mower using a washing machine motor he mounted on the old push mower. The kind you pushed. He put a speed reducer on and it worked great as long as you didn't cut the rather long cord. We actually had to snip the edges with one of those lawn clippers on our knees, Remember them you old farts? Now I complain the whipper snapper lines die before my wife is done and I need to get out of my chair to change it for her. Man I work hard.

 

[Old Ironmaker]

MODS. When I go back to check if my post loaded I get Restore or decline. So I restore thus the double posts. The last few wekks or so. Thought I'd give a heads up.

 

[southkogs]

I'm getting the same box - after you do a post, and you see the header at the top of the editor box? I'm not sure why it's doing that. I haven't had any double post on me yet.

iboats_tim ^^^ might take a look.