Replacing 1983 Seafarer floor/gas tank

[mashenden]

Wow - this post definitely gives me cause to take a closer look at my gas tank project. In my '93 Seafarer, there was at least epoxy all the way up in the tank area and, if I recall correctly, some grade of glass.

Regarding the condition of your tank, my guess is that 25+ years of moisture did it in. Generally a 80s vintage aluminum tank will have reached the end of its useful life if not well maintained (kept reasonably dry). Of course there are exceptions. If you are interested, I posted my approach and a parts list of installing a 58 gal poly tank in the auxiliary bay. I plan to use it as the only tank, and once the old tank is removed, I will hinge the rear floor board, add some form of water gutters and use the main tank area for storage. With my 4 stroke, having the tank a bit further forward was a plus.

Here is my post http://www.greatgrady.com/forum/viewtopic.php?f=2&t=15222#p102340

 

[mac83]

I've done some more work. Earlier this week, I got the gas tank all cleaned up. It actually look pretty good. There are a few spots that need to be welded. A little bit of corrosion but it's going back in the boat. I've almost got everything preped for the new main stringer to go in. I need some opinions on what type/brand resin I should go with. Since I've been deconstructing everything, I have found a little flex on the port side floor. I think since I'm going to be doing all this I'm going to cut a large rectangle so I can access everything on the port side that I can't see because of the foam in place. I'm going to go ahead and replace all of the thru-hulls w/ plumbing. When I was ripping out the port side main stringer, I can see that (what I think is) capped the stringer. There is what looks likes like folded fiberglass soaked in resin. I think this is the only thing that is holding the floor up. When I look under the floor, it appears that the side stringer is not touching the floor? Can anyone help confirm that? I'm getting my 1/2 inch marine plywood this week. I wanted to go ahead and get some resin and glass. Can anyone help me with a starting up list so I can get some supplies to get started. Thanks. I'll be posting up some pictures soon. This is going to be a complete rebuild.

 

[richie rich]

1/2 inch or 3/4 inch? I believe 3/4 inch ply is more common for the stringers......depending on how far you are going you will need at least 10 yards of 50 inch wide 1708......and at least a 6 gallon kit of epoxy with slow hardener. Marine Epoxy is a good resin for the money. You will need at least 1 roll of 12 oz biax tape for the tabbing, 6 inches wide. Get some milled fibers and some wood flour for making thickened putty for fillets. This is just to start....you will need more of the same the farther you go.

The rolled up glass and resin is how Grady bonded the deck to the tops of the stringers and fill the gaps. Take good measurements and pictures at every turn...it helps......Grady also suspended the stringer above the hull about 1/4 inch, give or take.....if you're re-doing everything, you will bond/bed it to the hull and make big,wide fillets with thickened epoxy to spread the load and avoid potential hardspots. If you want to suspend them as the factory, you will need to suspend them with foam or something while you tab in the 12 oz and cover the rest with the 17oz.
You can get all this stuff and more at the BBC website I posted earlier.

 

[mac83]

I've made a couple different measurement on the stringers and everywhere I measure, I'm only getting 1/2 inch...I thought they would be 3/4 also but they are not.

 

[richie rich]

It is what it is then....I would make sure to use plenty of glass for strength...3 layers of 12oz tape for tabbing all the edges and corners and 3 layers of 1708 to cover the stringer and the tabs to the hull. You can calculate the total glass requirement that way.......if you're doing the transom, you'll need at least 5 layers to get the right skin thickness. At a minimum always replace the original skin thickness plus whatever you sanded off from the remaining skin when prepping.

 

[mac83]

I think I want to go with poly resin but I dont see any on that boat building site? Is there a good place to get it. At this point I'm not doing the transom...I'm solid.

 

[richie rich]

Poly resin is fine for new or virgin glass layup...the whole boat is built from it...but it permeates water, and is a poor combination when used with wood...thats why its rotted in the first place....anyone who builds wood composite or cold molded boats uses epoxy for that reason.....if you insist on poly, at least use Vinyl Ester resin as its a hybrid that is better against water permeation and is good for secondary or mechanical bonding to existing glass....Polyester is NOT a good adhesive. I spoke with a Grady engineer a while back and he specifically recommended VE or Epoxy to repair their boats, not polyester for the reasons mentioned above. The site I recommended doesn't sell polyester resin because they build and repair everything with wood and epoxy.....you can probably get it through Jamestown Distributors or someplace like US Composites......

 

[mac83]

Well...I did not know that. I will be reconsidering.

 

[NOTHING ELSE MATTERS]

I will second the epoxy resin versus VE or polyester, it is a much better choice.
FWIW, check again the thickness of your stringers, i say this because when i restored the 1972 192 Grady, they used 3/4 plywood for stringers, so i would i assume they should of used the same for your boat.

 

[mashenden]

I will second the epoxy resin versus VE or polyester, it is a much better choice.
FWIW, check again the thickness of your stringers, i say this because when i restored the 1972 192 Grady, they used 3/4 plywood for stringers, so i would i assume they should of used the same for your boat.

I third the use of epoxy - much better as an adhesive and has tighter molecular structure to keep water out. I also second the 3/4" ply.

 

[Grog]

I would also use 3/4" for the stringers, I doubt they used 1/2". You can use the 1/2" for your hatches which also look like they should be redone. Epoxy is waterproof but save yourself and don't learn on it sooner or later your going to have something kick too fast and make a mess. Do the hatches first and learn on those with either poly or vinyl.

 

[BobP]

The gas tank subfloor, the fixed deck core and floor cover core is 1/2 inch, bulkheads/stringers are 3/4 inch.

Another source of supplies is Raka.com. Call and ask for Larry for advise and ordering.
Epoxy resins, cloth, various supplies like silica, foam rollers, pots and mixers, spreaders, fiskars to cut 1708, 100 box large latex gloves. Chip brushes, acetone and denatured alcohol buy locally by gallon in box store or Ace. Look over website, but call to discuss and order.

When you cut the fixed floor, cut a U shape out with the open U on the gas tank side. Suggest you do it thru an area where it's flat, and big enough opening as you can make it so that another cut is not needed.

Larry can advise on quantities for the job.

 

[mac83]

Aight, so I started buying my supplies. I choose to go with boatbuildercentral for most of my supplies. I'm going to check on my stringer thickness tomorrow as I'd like to pick up my wood at a local shop this week. I'm definatly going to get two sheets of 1/2 inch right away and start working on my tank covers. I figure this indeed would be a great place to start to get some practice w/ the glass and resin. I'll keep everyone posted and get some new pictures up. Thanks guys.

 

[gw204]

Now way I would go through all that work and only put 1/2" ply in for the stringer cores. 3/4" minimum.

I started using vinylester resin earlier this year and so far, I like it much better than epoxy. Glass wets out much easier with it.

In terms of resistance to water absorption, yes epoxy is the best. But if you have so much water in your boat that you have to use epoxy to keep your stringers and bulkheads from getting wet, you have bigger issues to worry about. Get it dry and then take steps to keep it dry...

 

[mac83]

So I went out and measured the stringers again. This time I took a measurement straight from the one of the pieces of a capped stringer. They are only 1/2 inch. I can't believe that they only used 1/2 inch. Has anyone else found this? I'm not sure what I should do. If I use 3/4 I think I'd have to shave some of the foam on the outer stringer?

 

[gw204]

Pop the top man. It'll be easier in the long run.

 

[richie rich]

So I went out and measured the stringers again. This time I took a measurement straight from the one of the pieces of a capped stringer. They are only 1/2 inch. I can't believe that they only used 1/2 inch. Has anyone else found this? I'm not sure what I should do. If I use 3/4 I think I'd have to shave some of the foam on the outer stringer?

Why would you need to shave foam? Can you show a better pic of where the replacement is going and how you mean to connect it with the remaining existing stringer? Like everyone has said, we've all seen 3/4 inch in our boats....but that doesn't mean that what you have is necessarily wrong....the thickness of the glass will pay a very imporatant role in keeping the boat stiff. You may want to contact GW to confirm the use of 1/2 vs 3/4.....Going to 3/4 shouldnt be that big a deal but you may be OK as is.

 

[mac83]

I'll be contacting GW tomorrow to see if I can speake to someone. I'm also thinking about how I will be able to reconnect the floor when I cut out the fixed floor sections to inspect and change all plumbing/thru hulls. Earlier someone said I should customer large 'U' shape cuts witht he open U toward to gas tank. Why is this a good cut to make. I have a small soft spot on the port side portion of the fixed floor so I'm thinking that they plywood inbtween the non-skid mold and glass on the bottom is rotted. What would be the best way to affixing that's fixed decking back in once all the repairs have been made. Does anyone know the thru-hull size? Are all three on each side of the boat the same? :bang

 

[richie rich]

Earlier someone said I should customer large 'U' shape cuts witht he open U toward to gas tank. Why is this a good cut to make.

Have no idea what this means....the port and starboard sides of the deck will have one side completely open, ie, where the tank is, and one end with a caulked seam, usually at the fishbox/helm......the opposite end will need to be cut at the transom bulkhead and the backside (opposite the fuel tank side) will need to be cut where your toe kick is, behind the teak trim to hide the cut seam. The 3 cut sides, when glued back down, will simply need a strip of ply glued in as a backing plate or splice to join and support both sides of the cut...think of a floor in your house where the joint between 2 pieces of plywood land directly over the floor joist to support the joint...thats what a strip of ply, centered under the joint will do for you when you re-assemble anything you cut out. That will keep the joint from "moving".....the rest of the deck will be glued down onto your new stringers just like the factory.

 

[NOTHING ELSE MATTERS]

Can you please post some pictures ?