floor repair decisions

Today I removed all the rotted wood from my transom and cut out the floor leaving 2" of the old decking all around the sides (see picture). I have chosen to use SeaCast composite material for the transom. I have received much information in another thread and decided to replace the floor using 1/2" exterior grade plywood. My plan is to put 3 coats of resin on the bottom then put a layer of glass mat on the top. Should I use Epoxy or Polyester resin for this?

The main decision I must make is how to connect the new decking on the edges. Should I screw strips to the underside fo the old floor to use as a support for the new decking and maintain the original floor level? Or, should I glass in the edges of the old decking to seal it, build up the stringers by 3/4" and just set the new decking on top of the 2" overhang of the old deck?

The stringers, much to my surprise, were hollow. There is a 1/2" thick X 2" wide strip of plywood in the top of each for the decking screws, but the rest is just a hollow woven glass shell. Is this a common contruction technique?

Finally, as I pulled up the floor I discovered all the foam was completely saturated. This boat was carrying about 400 lbs of water in that foam. I removed all the foam today. My final question...do I need to replace the foam? Can I glass in some horizontal supports to give the stringers lateral stability adn leave out the foam? IF I need to replace the foam, what should I use? And, how do I prevent the foam from getting wet again and holding water?

I appologize for all the questions, but I want to do this right the first time so I can have years of trouble free boating.

Thank you all.

Kevin

 

The foam is required by USCG regs and to keep the boat from sinking in the event of swamping. You'll need a closed cell foam, typically a two part liquid polyurethane. It's available at most fiber glass supply houses and comes in different densities. The stuff I use is available at FGCI www.fgci.com a couple hours from where I live, but they ship.

Unless you require structural properties in the foam, the 2 pound stuff will have the most bang for the buck. A 2 gal kit will make 8 cubic feet of foam and provide 480 pounds of buoyancy. To figure out how much you'll need measure the area(s) you'll be pouring the foam into, and calculate the cubic footage (height x width x length) and order accordingly. The two gal. kit costs about $50 clams.

I'd be thinking again about exterior grades of plywood compared to marine grades. Exterior ply does not have good panel construction, is weak as a result and is prone to rot. You may find some MDO to use, it has a marine grade though the ply count and quality will not be as high, the construction is better then exterior and has a great face for painting. You could entomb ply in epoxy (not polyester) and sheath it with cloth (my choice) or mat.

The stringer is really a tabbing with a nailer 'glassed in for the sole. This is the right way to attach the sole ply to the hull. The ply was blocked in place and saturated tape or chopped glass packed in under it to support it and tie it into the hull. The sole would be attached to this, sometimes then also tabbed to the hull. This forms a watertight seal around the sole to hull joint that is structural, seamless and watertight. The hollow tube as you've described means it's a structural part of the design. In most cases the sole material is glassed to the tabbing.

When your boat was built, the jury was still out on polyester sticking to wood. It's now in and it doesn't. If you want it to last you'll need to use epoxy. It's much stronger, more water tight, and of course more costly.

Also measure the old sole material again, I'll bet it was 5/8" which will measure around 9/16" on the tape measure, whereas 1/2" will measure around 7/16"

Personally, the down and dirty way is to cut all but a few inches of the old sole out (leave a few inches around the edges where it meets the hull. Replace what's necessary and screw down a new sole in good ply, using the old sole edges as a landing for the new sole (there may be a need to scab in some supports to make up the difference in the old and new installed height of the sole) glue and screw it down. Then glass it all up onto the hull sides with epoxy and cloth. This will seal in the sole and provide some additional strength with the extra tabbing (going up the hull sides a few inches with the glass)

New astro turf and replace the furniture and hardware and you're set.

 

Foam it is

Based on your info I will replace the foam. Thanks for the link to FGCI. I will also check locally to see what is available.

My friend had suggested using the remaining 2" of the old sole as a support for the new floor. Along with your input, I think that is the best solution. This also gives me an oppostunity to lay a new strip of wood on top of the stringers and glass that in for a new surface to catch my deck screws. Of course I'll glass in that new wood strip.

Unfortunately my picture doesn't show the stringers up at the bow, but I discovered that is how the water got into the foam. The two middle stringers are not sealed at the front, so any time water got to the front of the boat it could have found it's way into the foam. I'll be sure to run some cloth across that and seal it to prevent further water accummulation. Does this sound reasonable? Or, does the underside of the decking and the foam need to be open to the air for any reason? My primary goal here is to prevent the foam from taking on water again.

Also, I'll check the thickness of the old sole tonight. I thought it was 1/2" but it looked thicker than that and could be 5/8". Boat building is not very common around here, so marine grade ply will be hard to come by and if it is available will probably cost far too much for the budget of this project. I will check into MDO (medium density overlay....right?) and see if it is available. IS this also an exterior grade ply like CDX?

Thanks for helping a shade tree amature boat builder!

 

The lip on the old sole has to be sound and a good idea if it is. The foam you have is an open cell type and will pick up water. It takes forever to dry out if it ever does. Seal it in as the last thing you do before closing it in with the new sole.. This will give it as much time as possible to drip out the water. A few well placed holes can speed this up.

Marine grade ply can be ordered. Specialty wood shops can order it for you, maybe the local lumber store. MDO isn't the crap CDX is. It's a marine grade resin faced ply that is used by sign painters. It's designed to be used outdoors, survives very well and I'm using 1/2" to replank a 40 year old lap strake power boat right now. If you were closer I'd order what you needed with my shipment and you could pick it up, but . . . Exterior grades are designed to be covered with something, like aluminum or vinyl siding, stucco, brick, etc. and usually have a vapor barrier (Tyvek house wrap typically) between it and the covering, keeping away from the real exterior, the weather while allowing it to breath. Some grades of exterior ply can be used in direct exposure to the weather like T1-11 and some of this can be good stuff, but it's been a while since I've seen good construction on T1-11.

Marine grade just means the ply is constructed differently then other grades. The APA (American Plywood Assoc.) rates their grade as having all Doug. fur or all western Larch (great rot resistance). There are some other requirements, like the amount and type of defects allowed per layer, per faces, voids, etc. These requirements insure the quality is high and that the product can be counted on to perform to the specs set.

Construction grades have a much lower set of standards and the wood quality, panel construction, defects, etc will be much less acceptable in a marine environment. Sheathing a house in ply is one thing, expecting the ply to keep your feet dry on a lake, river or bigger puddle is another. In your case the sole is reasonably flat (if well designed should have a slight crown built in to control water runoff) and a lesser grade of ply may work without the troubles other boatbuilders have trying to bend poorly constructed ply (it just breaks at the voids or other defects) In the long run you'll be fine with MDO. I'd not bet on the exterior grade, but I would the MDO or other marine grades.

So hit the phone book, the web and the local marinas. They'll have the local suppliers and know where and what is available. Try the local sign painters too. A lot have switched to man made products for their bases, but many still use MDO. They may have the few sheets you need in house. I'm not sure where in Illinois you are, but the state has a big boating industry on several rivers and the big lakes. Dig deeper, they're out there. Builders are a quieter bunch then other industries and you may have to do some investigating.

 

Thanks again

Our Menard's store (similar to Lowe's, Home Depot if you're not familiar) carries 1/2" MDO for about $48/sheet. Does that sound about right? We have other local lumber yards that I need to call as well. I spent my lunch hour browsing the store yesterday and the difference in quality between MDO & CDX is staggering. I believe I will go with the MDO.

All of the old foam is gone and off to the dump! I calculated I will need 9.25 cubic feet of foam, so that should only be about $60 from FGCI. Again thank you for pointing me to them.

Sunday I pushed the hull outside in windy, sunny, 80 degree weather and the remaining sole dried out very well. It feels sturdy enough to use as a support for the new sole. I will spend the rest of this week building up the stringers and replacing a stringer that ran down the keel.

Thank you again for your great information. I hope to soon build a simple web site that will chronicle the rebuild so you can get a better look at this project. I'll keep you posted on the progress.

Kevin

 

Keeping up with you...

Thanks Kevin!

I have been reading your posts and learning alot. I have a '70 23' Mako that is beautiful! However, I have a problem with water in the bow and the foam that is there is soaking it up terribly. The more I look into some of the inspection hatches that previous owners have installed, I can see that replacing the deck, stringers, is iminent.

Which is not a totally bad thing. This is my first boat. I am excited about what it can be when I am done. But, I too am a novice.

My question is this:
I have a simple floor design. It will be easy to cut the edges of the flooring all the way around, bow to stern. I will probably leave myself about 3-4'' as a lip to lay the new deck on top of. After I have cut the deck, how did you remove the deck? I am sure that the deck is attached to the stringers with something (resin). Did you remove the deck in pieces? I am just afraid of screwing up the hull trying to remove the deck. I have photos of the deck in tact as I have not started yet...still building my nerve up to do this. If anyone is interested, I can post for opinions.

Thanks again for everyone's input and advice.

Kenny

 

Floor Cutting

The floor was extremely easy cut. Scribe a line on the old deck using a Sharpie or grease pencil. You can do this freehand or use a ruler or stick to keep your 3" or 4" distance consistent. Since you have inspection holes you know the overall thickness of the deck + glass. Now just set your circular saw to that depth and rip away on the edges.

Measure 48" from the transom on the old decking and look closely; you'll most likely see a line running side to side on the deck. If your boat was built like mine they just cut a 4 X 8 sheet of plywood to width and laid it in. If not, then just pick a distance, stike a line, and cut across the deck with your preset circular saw.

To pull up the old deck I used 2" wide X 16" long "J" shaped flat pry bars. My old decking had a layer of resin on top of the stringers and was nailed through to the plywood in the top of the stringer. The old resin was nasty enough that a good quick pop of the pry bar made it come loose. Once the first section came up I was able to use a combination of pry bar and "ARMstrong" prying to pull up the other two sections.

I called the guys at FGCI.com yesterday to inquire about the foam. The price they gave me was about $75 for a 2 gal. kit. The guy was extremely helpful and recommended I look at the American Composites Manufaturers Assn. website to find a manufacturer closer to me. The nearest one is in Green Bay, WI and they only have 10 gal. kits (5gal of partA PLUS 5gal Part B). There stuff was going to be $300 plus $75 shipping and would be a lot more material than I need. So, keep that mind Kenny when you're looking to find foam to replace your old saturated stuff.

Kevin

 

Floor Removal

Ok, sounds easy enough.

Now, once the deck is removed, and I can see the hull interior and rotted stringers. I can see the wood that was orginially used and encased in fiberglass. If I am using the Seacast product, do I need to remove all the wood and pour the seacast stuff into the area of fiberglass that encased the wood, let it set, then fiberglass the top all the way down the length of the stringer? I am probably ahead of myself as I need to go ahead and get the decking off to see what is actually down there.

Once I get the deck off, I'll post a pic of my problems and let all who can help chime in.

Thanks again for your reply, love this site.

I am finding out that just because the guy at the boat shop tells me to get rid of the boat, that this is not necessarily the case. With a little time and effort, and a little more money, this boat is going to be great when I am done.

Can't wait!
Kenny

 

Boat shops...depends

It often depends what boat shop you talk to. However, most of them are correct in telling you to trash the boat.......of you are going to pay to have the work done. Many older boats like ours are rotted and/or damaged to the point where it takes enormous man-hours to bring it back into shape. If that work is being done @ $45/hour you'll quickly go broke.

Between the engine rebuild, the floor and transom replacement, seats, carpet, etc. I'm going to have about $3500 in my boat. And, I'll have about 100 man-hours invested. $3500 isn't so bad, but if a shop did all the work, $4500 labor would make no sense for a 23 year old boat and engine. You can buy many nice, newer runabouts like my boat for $8000. However, you cannot buy one as nice as mine will be for $3500. That's why I chose to do this project.

Most any boat is salvagable, it's just a matter of how much time and/or money you're willing to invest. I bought my boat, motor (blown at the time) and trailer for $225. For that money I didn't have much to lose. The main thing I will have is peace of mind. I could have bought a used boat with who knows how many hours on the motor, old seats and unknown floor, hull, and stringer condition. Instead I'll have everything in new condition for about $2000 less than I would have paid for a used boat. However, the only thing that made this possible was my sweat equity. As I said early, I would have gone broke having a shop do all this work.

Enjoy your project. I hope to build a quickie web page this weekend to show my progress.

Kevin

 

KPeakman, I'd be careful about using untested products to perform tasks it is ill designed to address. SeaCast is a new, largely untested product, unless you buy into the advertising hype of it's sales staff, the web site offers little to support it's product other then testimonials from "overly pleased customers" no real data, no comparisons to other products or techniques. I couldn't even find a weight per gallon on the site, let alone the products strengths, be it tensile, flexural, compressive, Barcol hardness, water absorption, heat distortion, etc.

I'm still waiting on samples, testing data and performance specs on the stuff, but it appears to be a high solid content resin (a long chain polymer) Pound for pound you'll be hard pressed to beat the wood that was there. It's rather likely you'll pay a dear weight penalty using this stuff for structure other then the seemly limited uses polyester, polyvinyl and epoxy resins are used for in the near pure pourable form (thickened or unthickened resin)

The strength may come from the resin acting as a core in a sandwich construction and there are much better cores then solid resin. The idea of pouring a magic material and poof a stringer, engine bed or transom is born is lovely, but not terribly realistic. Sandwich construction requires the skins to be very strong and the tabbing holding on to the wood stringers, beds and formers in your boat are relying on the wood for its strength, not the skin and core composite construction you are thinking about replacing it with.

Maybe I'm wrong about the stuff, but I'll wait until the jury comes in on the it before I venture farther from shore then I can swim back to, with it between me and Davie.

The reason your stringers rotted was the boat manufacture that built it didn't wait for the jury to come in and went ahead and used polyester to glue and tab wooden structure into your boat (and hoped for few leaks before it was trashed). The jury is now in on that subject and it don't stick, this is why a bunch of boats built form the 60's up have rotten wooden structure. There is a fix for this problem, not hard, but it ain't pourable.

 

Transom Repair

Par,

I have 92 Chriscraft 232 Crowne that turned into a project boat. Replacing a little rotten plywood on the bulkhead turned into removing most of the bulkhead, the stringers and crossmembers in the engine compartment, and the transom wood (the exterior fiberglass is OK on the transom). The transom fiberglass ranges from 3/8" thk at the top to 1/2" thk at the bottom. I am a little concerned with bonding the plywood and getting 100% contact to the existing fiberglass. Is it acceptable to keep laying up fiberglass to acheive total thickness? I understand Ranger boats offers a solid fiberglass transom.

Lou

 

Stringer, Foam & Deck Replacement

Thanks to everyone for all of the val. info. I have a '87 Wellcraft 210 Classic that I have begun to restore. I have a few questions and hope someone will be willing to give me some good advice. I am a novice and have never rebuilt a boat before but have been researching this for a while. Some of the advice that I am being told and reading about seems to be conflicting. 1. What type of resin should I use? Some of the sites I have been to, say to use polyester but in many postings I have read I see negative comments about it. 2. What type of wood should I use for the stringers/ supports? It looks to me like the wood that was used was marine ply and not a solid hard wood. Was the wood just intended to be used as a form for the foam, and a fastener for the deck? Is the foam intended to be structural as well as act as added floatation? I will also be glassing the deck and would like to know more about Gel-Coats and how to texture certain parts for anti slip caricataristics. Sorry about all of the questions, but it looks like have finally found the place where I will get the right information.
Thanks, Dan

 

Use of composite flooring

I also am replacing the floor and complete interior in my 1988 Ski Brendella Tournament Boat. I am considering using an composite or aluminum honeycomb for the flooring. My logic (it may be flawed but it is mine) revolves around saving weight, improving weather/environmental durability at a realized increased cost.

 

I would used High Density Polyethylene (HDPE)

Everyone I am getting ready to replace my deck and I am going to use High Density Polyethylene (HDPE). It comes in 1/4 all the way up to 1 1/4 x48x96. The 3/4 I will use cost around $85 which means no having to use resins,expoxys or fiberglass..this stuff will not....

•less maintenance •machines like wood
•will not rot •will not absorb water
•dampens vibration •lighter than water, so it floats!
•totally recyclable •formable into curved shapes
•sound absorption properties •impact resistant
•does not delaminate •environmentally friendly
0accepts staples for upholstery •high strength to weight ratio

search kelron or codomo using google and you will find it...

 

I absolutely agree with PAR;

1) epoxy is a must for laminating the plywood
2) Use the right kind on marine flotation foam (closed cell, 2 lb. density)
3) There are much better materials for a transom than solid resin (plywood, or high density foam 14 to 20 pound 1.5" to 2" thickness)

Best of luck

Joel
Boatbuildercentral.com