Deck replacement on 1995 AS Explorer 245 - advice needed

[msteinkampf]

My family has been complaining that my 1990 Montauk 17 is too small for the fishing we do, so I brought this home last week – a 1995 Aquasport Explorer 245 with twin Yamaha 150 HP engines.



It had been sitting under a pine tree in central Mississippi since 2017. The transom is solid, the engines are in pretty good shape considering the circumstances, and the trailer was good enough for the 200+ mile trip home. I didn’t pay much for the boat because of this:



Apparently, a previous owner had sought to deal with the deck sagging by cutting open the “coffin lid” and inserting planks between the deck and the stringers. I could find no trace of sealant or fiberglass on the cut edges of the deck, and the exposed plywood is clearly rotted, as shown here.



The deck is soft from the helm to six inches in front of the fish box in the stern, from one side of the hull to the other. The helm seats and adjacent cooler boxes seem firmly attached to the deck. The coffin lid is delaminating, and here was the owner’s solution – new plywood and a dab of 3M 5200.



My plan is to cut out the deck and replace the rotted plywood. I’d like to keep the coffin lid as removable in case I ever need to swap out the tank. Now, I’ve looked at several tutorials here and elsewhere online, but none of them are on an Explorer. (I realize there is a good reason for this, as most owners treat their boats better than the previous owners of this boat did.) I’m not sure how to deal with the helm seats/coolers. Do I just cut around them and leave them in place? Should I expect to find rotted wood under them as well? Just how are the seats/coolers attached to the rest of the boat?

Any advice from those with experience in this task would be greatly appreciated. This project begins tomorrow with removal of the planks and drainage/removal/inspection of the fuel tank.

[Capt. Bob]

Well you got a lot of stuff going on here.

First, it appears the fuel tank "coffin cover" was cut and removed by the PO. That may have been to address the soft deck or....replace/repair the fuel tank. In either case, I'm guessing the tank coffin has taken on water and that is another problem altogether.

Aqua stopped using a removal coffin cover in the mid 90s (you know that already) and tank replacement then required the cutting of the deck to access the tank. They left a 'shadow seam" in the approximate area of the old cover but that was for show. Most tank covers experienced decay due to improper sealing of the deck access plates. There are a number of cover repairs in the forum and they are very straight forward in that respect.

The rotted wood on the tank top touching the aluminum surface ain't good. It leads to "crevice corrosion" as does water in the coffin itself that finds its way between the mounting straps. That stated, since the deck is cut, I would remove the wood, drain the tank and lift it out of the coffin. If you find no corrosion present, you can remount the tank correctly otherwise it will need replacement.

Typical tank sitting in water present in coffin:
https://classicaquasport.com/smf/index.php?topic=4608.msg30182#msg30182

The seats and "cooler/bait well" areas are molded and you should not need to remove these. Check the seat mounts. I can't remember if they had a sandwich of plywood underneath for mounting purpose. You can access those through the bait/cooler hatches.

The transom may be composite. There may be wood in the upper areas on each side but Aqua switched to composite pour again in the mid 90s.

This is a start.

Good luck.  

[msteinkampf]

Thanks for the advice. I contacted the PO - apparently an owner previous to him had cut the deck for reasons unknown. The PO said he thought it had come from the factory like that (-nope-). I cut out the wooden supports and pulled the tank after draining 75 gallons of fuel, which appeared to be gasoline premixed with 2-stroke oil. There was no water or sediment in the fuel and no sign of corrosion on the tank interior.

Tank appears to be original, with build date of May 1995. It is coated with what looks like a zinc primer.



There were no signs of corrosion or previous immersion, as shown here (with some water condensed on the tank bottom exterior). The neoprene pads were all firmly attached.





All the hoses and clamps appeared new, and a valve for one of the fuel lines had been replaced.
Except for the leaves and pine needles, the tank compartment looked great. There were PVC pipe drains forward and aft. The tank straps had been removed. The base on which the tank rests was solid and intact.



After inspecting the tank, I am inclined to just seal up (with fiberglass) the coffin lid rather than trying to convert it to an easily removeable piece. I would say this installation is confirmation of the Pascoe method of tank installation (https://www.yachtsurvey.com/fueltank.htm).

I took a closer look at the area under the seats and cooler/baitwells. The deck transitions to about ½ inch of solid fiberglass in that area, and there is no wood underneath them, nor is there any support from below.
Transition from the helm seat support (on right) to deck. Note the absence of wood under the seat platform.



The plywood in the decking is damp and completely rotted, I could insert the shaft of a screw driver all the way in and pull out squares of rotted wood.



I am convinced that the water in the deck came from infiltration at the site of the coffin lid cutout, which had almost no sealant around the cut. Why the deck was cut in the first place remains a mystery. Perhaps it was a misguided attempt to reduce the “bounciness” of the deck that is known to occur in Explorers due to suboptimal assembly techniques (as documented by seabob4 here: https://classicaquasport.com/smf/index.php?topic=6124.msg42196#msg42196). The overlying fiberglass and gelcoat are in very good condition, and I assume the fiberglass under the plywood is in good condition, too, so why not cut out the deck, remove the bottom fiberglass and rotted coring, install new coring and glass under the top fiberglass layer, and re-install it? I haven’t seen any rebuilds on Classicaquasport.com that did this, but I did find this approach documented on another site (https://www.floridainshoreangler.com/tactics/fishing-structure/how-to-pier-fishing?id=343). This would be easier in my boat because I would not have to remove the deck in one piece. Better yet, why not cut the top layer of the deck, pull it away from the underlying rotted plywood, replace the coring, and reinstall the fiberglass/gelcoat? I found one tutorial on BoatworksToday (https://www.youtube.com/watch?v=JAtjHjJhBV0&ab_channel=BoatworksToday) where Andy did just that, although I think his technique could be improved upon. I believe the first approach would be useful if the foam under the deck needs to be removed, but the second approach would be preferable if the foam were to be left in place. The foam lateral to the stringers on my boat seems dry, but I intend to confirm this at my next work visit.

Your comments about these options for deck coring replacement would be appreciated.

[RickK]

There is another way to repair the deck. Copy and paste the following into a google search box - injecting resin into boat deck +site:classicaquasport.com/smf

[msteinkampf]

I reviewed that technique and decided the coring was too far gone for it to be effective. Thanks for the suggestion, though.

M

[msteinkampf]

Here's an example of epoxy injection failure when tried on a badly rotted deck. https://www.youtube.com/watch?v=WWQRZpah_0M&ab_channel=SailboatCareandRepair

[Capt. Bob]

You are correct in that there are really no (maybe one if I looked hard enough) Genmar deck rebuilds here but the method of stripping the old sandwich of plywood/balsa off the gelcoat top deck is common when dealing with the old style removable tank coffin cover. There are several documented here that utilize this method just on a smaller scale. In your case, that would be what I would do.

Good luck.

[rhtrades]

replaced a large section of rotten core on my Expolorer.  cutout the top piece of deck with a multi tool, scraped out all the wet core, replaced with marine ply (epoxied in with G-Flex) and then put back the piece of fiberglass deck that i cut out.  It's actually a real simple process, but is alot of work.

The only problem I'm dealing with now is the seam printing through (cracking).  I will have to sand off the gelcoat I used to cover the seams, epoxy a thin piece of fiberglass cloth and re-gel. 

Getting the seams to look good is the most challenging imo, as it is a cosmetic  and want it to look good.....I may just put some SeaDek over that entire area to cover it if the seams crack again.   

[msteinkampf]

Good to hear that someone else has tried fixing the deck while leaving the bottom layer of the laminate. As best I can tell, the foam underneath my deck is dry, so I'm going to go with this technique. Thanks for the advice.

[msteinkampf]

I decided to completely remove the tank from the boat for a more thorough inspection and to facilitate work on the deck.

The 1-ton chain hoist was overkill for this task, as the tank weighs only about 150 lbs, but it did make things easier when working alone without a forklift for the removal. $51 with a coupon at Harbor Freight, you should get one.




No evidence of corrosion on this tank. The neoprene strips on the bottom are intact, but the ones on the end of the tank have fallen off.




There is some rotting of the fiberglass-encased plywood that serves as a platform for the fuel tank. I am toying with the idea of just installing a PVC board over this with some 5200, but that would reduce my clearance over the tank by the thickness of the plank. Should I cut out and replace the board, or just install something over it?

[Ulysses485]

It seems like the center section was not laminated with glass, correct. To answer your question, I would definitely get it out of there and replace it with same or composite material and glass it up solid. Considering its the base for the fuel tank to sit on, you don't want to have to ever get to it again. Your there already so might as well make it solid. It also acts a a mini bulkhead for the strength of the v. If you do decide to use plywood, make sure to glass both sides so it never gets water inside so it doesn't rot again.

[rhtrades]

Is there a hole that anywhere in that space that goes down to the Bilge?  just incase if water does get into the fuel tank area, it won't sit around in that area but rather, drain into the bilge......

[Capt. Bob]

Is there a hole that anywhere in that space that goes down to the Bilge?  just incase if water does get into the fuel tank area, it won't sit around in that area but rather, drain into the bilge......

So how this works (by design) is that water flows from the forward bilge through the tank coffin into the rear bilge compartment. The rotted section that was under the tank rides above the center line (keel) of the hull which allows water to pass underneath. Since this is connected from front to rear (through bulkhead openings, water can pass both ways.

The best way to ensure tank longevity is to keep the tank coffin as dry as possible. That means the coffin cover (removable on older models) is correctly sealed including any deck access plates. Second would be to reduce or eliminate water from passing through the coffin itself. When I replaced my tank in my 210, I plugged both holes fore and aft in the coffin. Of course there are bilge pumps in both the front and rear to drain any water from those compartments.

Looking at the tank pics, I would be suspect of the areas where the mounting straps came in contact with the tank and inspect these areas for pinhole corrosion that is cause by the water being trapped between the two surfaces. 

[rhtrades]

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?   

[msteinkampf]

Yes, the tank compartment is connected to both forward and rear bilge compartments by PVC tubes. Currently, there is some water in the forward bilge that is the color of rotten wood. Due to the hull design, one must elevate the bow quite a bit to get that water to drain to the stern. There is a bilge pump in the forward compartment. I am inclined to follow Capt. Bob's advice to isolate the tank compartment from the forward and aft bilges, but I would like the option of draining the compartment to the stern if I get water intrusion in the future.

I was afraid you would say to replace the tank deck. I agree, it should be done. Now, I have some experience with repairing marine electrical and mechanical systems as well as gelcoat repair, but when it comes to actual fiberglass repair, my experience is ... zero. (Perhaps this will be a good project to learn on, since cosmesis will not be an issue.) I've got the tools to cut out and grind down the old platform. Assume that I will be replacing it with a 0.75x9.25-inch PVC board like this one: https://www.lowes.com/pd/Royal-Building-Products-0-75-in-x-9-25-in-x-12-ft-PVC-Trim-Board/5002027507 reinforced with fiberglass, and that I will be using epoxy. What would you recommend for the fiberglass layup schedule?

M