Deck replacement on 1995 AS Explorer 245 - advice needed

[RickK]

Can you take a pic of the bottom of the tank lid? On most there is endgrain balsa covered with fiberglass which tapers down to the bottom of the back (imagine the lid laying upside down). What you do is use a cutting wheel to cut through the taper where it meets the lid glass. Then pry the fiberglass and coring off the lid base glass. Grind the remnants from the lid base and then you can use whatever coring you desire (with the edges bevelled at a 45 degree angle) and then 2 layers of 1708 for stiffness.

[msteinkampf]

As previously noted, the tank lid was “repaired” by the PO, who glued with 5200 a piece of plywood between the two layers of fiberglass. I’m going to repair the tank lid as you describe later, but what I must do first is to repair the board underneath the tank. I’m thinking about scuffing up a PVC plank, wrapping it in fiberglass cloth/epoxy, and then tabbing it in place with additional layers of cloth. Would 1708 be OK for this, or would something else be preferable, as I have read that 1708 doesn’t wrap around edges very easily.

[msteinkampf]

Well, perhaps that question was a bit naive, like “could you teach me how to lay fiberglass?” I’ll be back in touch after I read this: https://www.westsystem.com/wp-content/uploads/Fiberglass-Manual-2015.pdf.

[RickK]

Sorry, I should have gone back a page and saw the lid bottom. Are you going to use poly or epoxy on this boat repair? Yes, 1708 doesn't like to bend around sharp corners.  You could use 1200 - doesn't have the CSM on it and should bend easier. If you don't have a good supplier around you we have US Composites down here on the east coast. They have a lot of stock, the freight can be brutal though for heavy gallons of supplies (bet I paid $500 or more in frieght over the years) - http://www.uscomposites.com/

[Capt. Bob]

Capt. Bob,

If water gets through the access plate (the one over the Fuel sender for example), would that water just sit around the fuel tank with no where to go or are you saying it will flow out, due to the description you provided regarding the front and rear bilge?   

Well if enough water got in then yes, it would its way out either to the front or back if the bulkhead passage were open. If the passages are connected with a continuous pipe then no.

My 91 passages were not connected so they could have drained and at the same time let water pass underneath the tank. The tank bottom support board was opened on each end (didn't run the length of the coffin). If the deck plates are properly sealed, very little water gets in. I open my plates and hatch when the boat is stored to allow air to enter and aid in evaporation. My setup is different than most as I have my batteries mounted below deck and forward of the tank.

 This is the way they built them (Genmar) in the early 90s. I reduced the tank size and used the gained area in the coffin to mount the batteries. The black starboard is a false bulkhead between the tank and batteries. You can see the factory passage at the bottom. It has an expandable plug with sealant.

[msteinkampf]

Rick, for the tank support, I expect to use PVC board and epoxy. For the deck, it’ll probably be Coosa and epoxy, and repairing the cut lines with gel coat over epoxy. I’m still working out how best to clamp the deck. Today I started poking a welding rod under the top deck skin to determine where I’m going to make the cuts. My goal is to cut about one inch inside of where the inner and outer deck layers are fused.

That’s a really clean tank compartment, Capt Bob.

[rhtrades]

Thanks Capt. Bob for the detailed explanation. 

I like what you've done with the tank compartment and using that space for batteries. 

[Ulysses485]

Rick, for the tank support, I expect to use PVC board and epoxy. For the deck, it’ll probably be Coosa and epoxy, and repairing the cut lines with gel coat over epoxy. I’m still working out how best to clamp the deck. Today I started poking a welding rod under the top deck skin to determine where I’m going to make the cuts. My goal is to cut about one inch inside of where the inner and outer deck layers are fused.

That’s a really clean tank compartment, Capt Bob.

Personally, I think epoxy is unnecessary in most cases, especially when using Coosa (because it works so well with Polyester Resin). West System literature looks to be a good resource but likely has a slight bias because epoxy is what I think they sell most of or maybe even don’t sell polyester resin at all. You mention Gelcoat over Epoxy which although debated in recent years with prep to “make it work”, has always been an incompatible bond because of amine blush from the epoxy and the different composition of materials. When using epoxy, stick with epoxy based paints. If gelcoat (a polyester resin based material) is your preference for a finish, stick with polyester resin for repairs. Polyester resin catalyzes with MEKP (1-2%) the same as gelcoat. My opinion (if trying to save cost and gelcoat is your preference) would be using polyester resin and either honeycomb coring (laminated properly/heavy), divinycell (4lb), or coosa (15-20lb). Lastly, your choice of resin might slightly dictate your choice of fiberglass materials. If you go with epoxy resin, a cloth material (w/o the mat…1700) will be easier to use. On the other hand, if you choose polyester resin, you will need the matt on the surface you are bonding to (coring, existing prepped glass, etc.) AND on either side of your biaxial or woven glass when its laid up.

With all that being said, I will say that epoxy has must better bonding strength (like 10x or something that of Poly) and waterproofing so it’s a great product for DIYers that inevitably don’t prep the surfaces properly or also want to use plywood as their choice of coring materials.

Lastly, finding a local supplier can also make a difference in what you have available to you because as Rickk indicated, freight charges can be pretty brutal.

Hope that helps.

Surely that’s a lot to take in and I was in your shoes at one point till I dove in only a few years ago. Feel free to ask questions and if hopping on a phone call helps down the road, I would glad to help further.

[msteinkampf]

Thanks for the detailed advice and generous offer. I guess am not so concerned about overlaying epoxy with polyester because I have done that routinely when filling screw holes for gel coat repair with good results, but I am still a ways from deciding. My plan is to peel off the top layer of the deck, remove the rotted core, and do a dry fit using inexpensive foam insulation board, which should help me determine how much core material I need to order. With a local distributor (Advanced Plastics) right down the road from the Coosa plant in Pelham, I’m hoping I won’t get killed with shipping charges on this project.

M

[msteinkampf]

The boat cleaned up nicely with some scrubbing and pressure washing. I think having it under a pine tree for more than a decade helped preserve the gel coat (while promoting deck rot).



I pushed a welding rod through the rotted deck core to determine where the deck was glassed to the liner. My plan was to cut the top layer of the deck about ½ inch medial to that joint so I could slip some core material past the cut line on reassembly. I took some measurements of the tank compartment, too.




Here are the cutting tools I had available for today’s tasks. I found the angle grinder with a diamond blade to have the best combination of ease of use and cutting ability. I used the oscillating saw with a straight blade (not shown) to finish cutting at corners. None of these tools was very good for cutting curves, though. I should have brought my Dremel tool with the thin router bit.


Before cutting the deck, I removed the rotted board that supported the tank. Note that the fiberglass tabbing does not extend all the way across the board to the other side. I don't think this board had any structural function except to help hold the fuel tank in place.






The board came out easily once I cut the fiberglass tabbing with the angle grinder. I'll grind down the edges later. Note to boat builders: coating marine plywood with a thin layer of polyester resin does not prevent the board from rotting.

Next step: Cutting the deck.

[msteinkampf]

Here is the first piece of the deck opened up. It came up easily except for one corner near the fish box that had been filled in with fiberglass instead of the plywood squares. The builders used a bit of end-grain balsa at the lateral edge of the decking (arrows). I guess it was easier (and faster) to break off a small piece of balsa than to saw a thin strip of plywood. All the wood was damp and foul-smelling, and it crumbled to the touch.


I was successful in leaving a recess at the lateral edge of the deck for later core insertion, but I will probably have to clean that up with the grinder. After removing the first piece of deck, it became apparent that the rot extended all the way to the scupper at the stern. I’ll have to cut that out another day.



After removing the rotten wood, I’m going to let the fiberglass layers dry out and then sand/grind them smooth.

Next step: more deck cutting.

[rhtrades]

You're doing a great job!  Looks pretty similair to how mine did.....Let me know what you do (or what you're going to do) to repair the seams after you place back the old non-skid you cut out.  My seams cracked/printed through after 1 year, so i'm going to grind them down, fill with GFlex epoxy then gelcoat when it warms up here...Hopefully that will do the job. 

[Ulysses485]

Coming along! Letting it dry it will help and ensure that any moisture doesn't get locked into any hard to reach areas. I don't know this hull very well and its hard for me to see the photos capt bob posted but couldn't that forward drain line be ran underneath the fuel tank subfloor so there isn't open ends in that area? Not sure if that makes sense.

[msteinkampf]

Ulysses, there are PVC pipes that connect the tank compartment to the forward and aft bilges. The forward bilge is quite deep due to the hull design, and I was unable to drain it completely by elevating the bow. There is always a little water there. I’m going to close the tubes with removable plugs to isolate the tank compartment.

rh, what did you do to seal/cover the cut line after you reattached the deck? Did you install the core so it runs under the cut, or did the edge of the core line up with the saw kerf? I’m thinking the fiberglass on either side of the cut should be ground down, a strip of fiberglass cloth and some polyester resin applied and covered with gel coat. I am not aware of flexible poly resin (glass plus resin is supposed to flex some), but flexible epoxy might be another option - you’ll have to top coat it with something, though.

[rhtrades]

I used 3M Marine High Strength filler (vinyl ester with glass strands) to cover the cutline after reattaching the deck.  I believe using this 3M filler was a mistake for that application.

The edge of the core lines up with the saw kerf...That was filled with GFlex epoxy...a good epoxy imo.  I used that to epoxy the core and the deck. 

I think I will do as you recommend, grind down the cut line and epoxy(w/ gflex) in a strip of fiberglass...once it dries, sand it with 80 grit and apply gel coat.  I called West Systems and they said gelcoat will adhere to Gflex epoxy as long as you sand it with 80 grit to create a mechanical bond.   

Let me know how you make out once you get to that stage as you'll probably get to that point before I do as the weather is not going to be conducive to that for another month or so....