1977 230 Robalo CC fuel tank replacement and general drainage questions

[erock1847]

First time on this thread.  I just bought a 1977 230 Robalo center console.  I got a great deal on the boat, trailer and motor.  The fiberglass all around looks awesome and the transom and floor seem solid.  I had about 8 gallons of water I siphoned out of the fuel tank which I think originated from the sending unit which had to screws stripped with standing water over the top of it and water still coming from the foam.  After I replace the sending unit I plan on doing a pressure test as I've read on here, but I'm not really sure how that's done?  It looks as if the tank was replaced before, since it has a metal plate over the area where the chairs were with a new bench?  I've done alot of looking on this site and have yet to find any pictures of any boats my size and period with the tanks and coffins open?  

Is this boat self bailing?

Is there a drainage system below the deck?

Thanks in advance for any advice you may have for me.

Cheers,

Eric

 

[Retainer]

I have a 1978 Robalo, check out my restoration thread. Your boat is basically the same boat. You should be able to see the scuppers, but my transom area was redesigned to eliminate the scuppers.

You should see a hole at the end of the floor that drains under the fish box to the back of the transom. If you have scuppers, it is self bailing. if you don't see scuppers, then you should have a bilge area near where the drain comes out from under the fishbox.

My floor had paint on it, I sanded it down and found your exact green color, check it out on my thread.

Your tank may have been replaced, only one way to tell. these boats came with 2 pedestal seats. I plan to install a leaning post too, after replace the floor which is soft. While I have the floor up, i plan to rip out all the wet foam and I will in all likelihood, i am 99% sure, replace the tank.

I have had my boat for 11 years now, and i am in the middle stages of a complete restoration. Good luck with yours. Pat

 

 

[erock1847]

Thanks for the heads up Pat.  I do not have scuppers in my transom, just some 3/4" holes right below the water line on the transom (unless those are considered the scuppers) and the deck does drain below the fish box and into the lower bilge near the transom.  It's currently configured with the bilge pumps on each side of back of the boat, which I believe are fish boxes, but one has all the lines coming from the center console to the engine.  NO bilge at the rear, near the transom thou? 

I have water that keeps filling up the access hatch to my fuel sending unit.  I suck it out with a shop vac and fills back up without any rain.  So I think the foam is soaked in there and keeps coming back to that point.  I was planning on just re-caulking the fuel hatch that had some cracks, but I feel like I should get the water out before it I seal it back up.   

I've decided to go ahead and pull the fuel tank cover and the center console to see the integrity of the tank.  I was hoping to get some intel on how much is involved with this process to get to the fuel tank and coffin.  It sure looks as if the tank was replaced at one point, so I'm hoping the tank is not foamed into place, but it seems as if someone has foamed it back in from I can see from the sending unit hatch and fuel line hatch under the center console. 

[erock1847]

[Retainer]

Yeah this was just a bad design by Robalo. Here is my transom well that has been modified.

[Retainer]

On 8/15/2018 at 10:14 AM, erock1847 said:

Thanks for the heads up Pat.  I do not have scuppers in my transom, just some 3/4" holes right below the water line on the transom (unless those are considered the scuppers) and the deck does drain below the fish box and into the lower bilge near the transom.  It's currently configured with the bilge pumps on each side of back of the boat, which I believe are fish boxes, but one has all the lines coming from the center console to the engine.  NO bilge at the rear, near the transom thou? 

I have water that keeps filling up the access hatch to my fuel sending unit.  I suck it out with a shop vac and fills back up without any rain.  So I think the foam is soaked in there and keeps coming back to that point.  I was planning on just re-caulking the fuel hatch that had some cracks, but I feel like I should get the water out before it I seal it back up.   

I've decided to go ahead and pull the fuel tank cover and the center console to see the integrity of the tank.  I was hoping to get some intel on how much is involved with this process to get to the fuel tank and coffin.  It sure looks as if the tank was replaced at one point, so I'm hoping the tank is not foamed into place, but it seems as if someone has foamed it back in from I can see from the sending unit hatch and fuel line hatch under the center console. 

I have a fabricated plate with a bilge pump attached which I silicone down on top of the rectangular bilge access hole. I also have a bilge down below in that access hole, but rarely does any water get down there.

[Retainer]

Getting the floor up requires disconnecting the T-top at the floor then leaning it forward. The deck should be in 2 sections. The first is from that deckplate just behind the console, there should be a seam just ahead of that plate but behind the transom. The other section sits below and inside the console. It is raised to allow for the fuel fittings and to prevent water from getting underneath the console.

imtrying to post some pics but having difficulty.

[Retainer]

You have what appears to be an aluminum or SS plate below your leaning post, I assume to support the post. That area can be removed but I’d get the console out the way to get that other part below the console up so you can examine the tank. It is likely foamed in. Check out my pics in my resto thread. I took my tank out and having a new aluminum tank fabricated to same specs with coal tar epoxy coating and will foam in the tank with closed cell foam pour.

[Retainer]

This is the section that would be under your leaning post

Edited August 21, 2018 by Retainer

[Retainer]

The hole in the deck at the bottom of the pic is your thru plate just aft of your console. It’s to inspect the fuel sender.

[Retainer]

Like I said, I think that plate was installed to give added strength to hold the leaning post. Don’t assume the tank was replaced. What you should assume is that your floor is rotted.

if you want to see if it’s the original tank, check the larger inspection plate under the console. If there are 2 fuel lines coming out, then it’s likely original as I understand the 23’ had an option to run twin 115s.

[erock1847]

Yeah, I took off the deck plate and found someone refoamed the top of the tank to the plate but didn't use closed cell foam.  I'm glad I went in there cuz the fuel fill hose and vent hose we're disengrated.  The foam smelled of gas.  I don't think they used Marine grade hoses.  I will replace all the hoses, replace plywood under deck hatch and fiberglass in place.  I think your absolutely correct about the plate being added for bench support.  After seeing how everything is supported in there I may just add it back.  See pics of the hatch removed.  I plan on adding a hose along the edge of the tank to a low point carved out of the foam along the tank edges to the stern of the tank and running to a hatch in the event that water gets in there I will be able to siphon out in the future without removing CC and deck plate.  Will post more pics later.  I think I have the original tank due to the 2 fuel lines and the closed cell foam still in place around the edges of the tank.  I plan on doing a pressure test after fuel lines are replaced, but I think it will be fine.  I also think these original tanks were internally supported so to transfer the load from the deck as it feels rather rigid in some places where you can walk on.  My deck plate is in one piece.

[Retainer]

Yeah that’s ugly. Same as what I found. That isn’t closed cell foam around the tank either. That’s the same foam used throughput the boat. I would replace the tank now that the floor is up. I just ordered a replacement tank, 93 gallons, coal tar epoxy sealed, they picked up my old tank and will deliver the new, for 1,200 from Patriot in Forked River NJ. 

The tank is 8” high. If you want to check out poly tanks, look on Eastern Marine. They have a great selection.

i went with aluminum because it doesn’t expand and contract, plus I plan to pour closed cell foam around the tank to hold it in place and to keep moisture away. The coal tar epoxy will make the tank last forever.

I ordered a 4x8 x1” sheet of composite to replace my deck. No rot. Plus I think when I screw in the new leaning post I won’t have to use backing plates. Each leg has 4 screws right into the composite. Nothing to rot and loosen the screws, etc.

[Retainer]

Oh and “that someone” you mention in the beginning of you post about installing foam but not closed cell.......that was the factory.

[erock1847]

I really find it hard to believe that they used open cell foam in these boats from the factory.  The foam around the edge of the tank seems a different color.  Almost white compared to the other foam found on top which was yellow.  I just looked up on the forum too where Mr Robalo replied that they did use closed cell foam and that you may find some wet foam around the edges where the foam broke down but generally speaking that the foam through out will keep out water.

Where did you get the composite board and how much?

Where do you get the foam?

Thx,

Eric

[erock1847]

Whoa...this stuff is expensive.  I think I may be using plywood and fiberglass to get this job done.  Seems like a great idea though. https://www.usplastic.com/mobile/catalog/item.aspx?itemid=31838

[2-N-TOW]

Erock -

You want to use something like divinycell, nida-core, or plascore.  Those hdpe sheets will not bond to any resin or epoxy.  With the coring material I mentioned, a layer of 1708 biaxial cloth on both sides makes for a very strong panel.  When this is bonded to the bottom of the coffin lid, be sure to first clean the lid and scuff it with a 36 grit sanding disc so as to create a rough surface for a mechanical bond between the coring/resin/cloth/coffin lid.  

Retainer -

Even when using a coring material that will have fasteners inserted, I would highly recommend adding a section of 1/4" aluminum plate in the core material where the fasteners will eventually go.  Cut a hole in the coring material where the aluminum plate will be inserted and bed the plate in a thickened resin.  Now take the plug of coring material and sand down the edges so it fits loosely in the opening.  Butter up the edges thoroughly and the bottom that will butt up against the plate and insert it, being sure some of the resin comes out of the joints.  The reason for this is to create a barrier for any water that may seep down those screw holes...it will only be able to migrate as far as the resin damn that is holding the plug in place.  Once it has set up, sand the bottom of the plug so it is flush with the rest of the coring, then cover the bottom with a layer of 1708 biax cloth.

When the time comes to re-install your leaning post, drill the proper size hole so you can run a tap down the hole and cut threads in the aluminum backer plate.  Install the correct stainless steel machine screws using some blue loctite on the threads and a squirt of marine silicone around the hole to make it as water tight as possible.

[Retainer]

7 hours ago, erock1847 said:

I really find it hard to believe that they used open cell foam in these boats from the factory.  The foam around the edge of the tank seems a different color.  Almost white compared to the other foam found on top which was yellow.  I just looked up on the forum too where Mr Robalo replied that they did use closed cell foam and that you may find some wet foam around the edges where the foam broke down but generally speaking that the foam through out will keep out water.

Where did you get the composite board and how much?

Where do you get the foam?

Thx,

Eric

A friend from the dock makes signs and such. He told me about it. $230 for a 4x8x1inch sheet. He is bringing it down Friday.

the closed cell foam pour, check with Jamestown Distributors or just google it. I got mine from my friend who knows my boat from 20 years ago and worked on it. He modified the transom. And he redid the floor deck about 15 years ago.

[Retainer]

1 hour ago, 2-N-TOW said:

Erock -

You want to use something like divinycell, nida-core, or plascore.  Those hdpe sheets will not bond to any resin or epoxy.  With the coring material I mentioned, a layer of 1708 biaxial cloth on both sides makes for a very strong panel.  When this is bonded to the bottom of the coffin lid, be sure to first clean the lid and scuff it with a 36 grit sanding disc so as to create a rough surface for a mechanical bond between the coring/resin/cloth/coffin lid.  

Retainer -

Even when using a coring material that will have fasteners inserted, I would highly recommend adding a section of 1/4" aluminum plate in the core material where the fasteners will eventually go.  Cut a hole in the coring material where the aluminum plate will be inserted and bed the plate in a thickened resin.  Now take the plug of coring material and sand down the edges so it fits loosely in the opening.  Butter up the edges thoroughly and the bottom that will butt up against the plate and insert it, being sure some of the resin comes out of the joints.  The reason for this is to create a barrier for any water that may seep down those screw holes...it will only be able to migrate as far as the resin damn that is holding the plug in place.  Once it has set up, sand the bottom of the plug so it is flush with the rest of the coring, then cover the bottom with a layer of 1708 biax cloth.

When the time comes to re-install your leaning post, drill the proper size hole so you can run a tap down the hole and cut threads in the aluminum backer plate.  Install the correct stainless steel machine screws using some blue loctite on the threads and a squirt of marine silicone around the hole to make it as water tight as possible.

I will print this out for my boat man, but I don’t have the post yet. A friend is buying it as part of his “contribution” to the resto. I wanted to line it up on the deck to mark it out but he didn’t buy it although he told me he did. So now the deck is up. Maybe I will just estimate it with setting up one of the old pedestal seats to get an idea where I want it. I’m getting(I hope) the Taco premium post with the flip up seat and fiberglass storage compartment 

[Retainer]

The product my friend suggested is Azek. Im concerned about the ability to attach the deck skin to this product. I guess 5200 would work? I’m researching nidacore and Plascore. Not sure though how well screwing in the leaning post will hold up. These products are honeycombed. Nidacore comes with a glassed 4x8x1 inch sheet at roughly 345$ from Merrit supply.

[Retainer]

The product my friend suggested is Azek. Im concerned about the ability to attach the deck skin to this product. I guess 5200 would work? I’m researching nidacore and Plascore. Not sure though how well screwing in the leaning post will hold up. These products are honeycombed. Nidacore comes with a glassed 4x8x1 inch sheet at roughly 345$ from Merrit supply.

[Retainer]

I researched the Plascore and Nida core products. They use an interior honeycombed pattern sandwich style. I don’t think anything can really be screwed into it and hold with any degree of confidence. I’m going with the AZEK solid recycled plastic and will use 5200 adhesive to attach the deck skin to it. 

I will have to see about the plates. I want to use them for the post but unsure at this stage about resin attaching to the product

oh it’s $199 a sheet.1” thick

Edited August 23, 2018 by Retainer

[2-N-TOW]

You are correct about the plascore and nidacore regarding screwing directly to them....with no prep work they will not work.  Another option I have heard of that works for the honeycomb material is to first glass it in place on the coffin lid, then drill your holes for the leaning post using the base for a template, being careful to not go all the way through the coring material..  Remove the base then re-drill the hole large enough to get the stainless nut through the coffin lid and top skin of the coring material.  Next, take a 16 penny nail, cut the head off, and bend it at a 90 degree angle so you have 1"  perpendicular to the shaft.  Chuck the nail in a drill, insert the bent end into the hole, and spin it with the drill to open the honeycomb walls immediately around the fastening point.

Make sure the machine screws are of a length that they will not extend through the bottom of honeycomb core.  Run the nut on the screw so when you put the fastener in the hole the nut is centered in the coring.  Remove the fastener and thoroughly coat the machine bolt with wax so resin cannot stick to it but not on the nut.  Pour resin into the hole until almost full and insert the bolt/nut combination into the hole.  If you can insert them through the leaning post base then the holes, that would be even better as the alignment would be correct.  Just put some tape on the bottom of the leaning post supports so it can be removed once the resin sets up.  By using the nail to open the cells in the coring, you have increased the surface area the nut will be exerting force over.

I honestly do not know how well Azek will perform as a coring material.  My concern is that, like all coring materials, a layer or two of fiberglass is necessary on both top and bottom in order to have an I-beam structure that will not flex when walked on.  Just attaching the top skin to the Azek will not be enough to keep if from flexing a lot; you need that bottom glassed to complete the structure.  As to how well resin will bond to it, I would suggest buying a small piece from Lowes or HD and glass a piece of cloth to it then see how hard it is to pull it off once it sets up.

[Retainer]

29 minutes ago, 2-N-TOW said:

You are correct about the plascore and nidacore regarding screwing directly to them....with no prep work they will not work.  Another option I have heard of that works for the honeycomb material is to first glass it in place on the coffin lid, then drill your holes for the leaning post using the base for a template, being careful to not go all the way through the coring material..  Remove the base then re-drill the hole large enough to get the stainless nut through the coffin lid and top skin of the coring material.  Next, take a 16 penny nail, cut the head off, and bend it at a 90 degree angle so you have 1"  perpendicular to the shaft.  Chuck the nail in a drill, insert the bent end into the hole, and spin it with the drill to open the honeycomb walls immediately around the fastening point.

Make sure the machine screws are of a length that they will not extend through the bottom of honeycomb core.  Run the nut on the screw so when you put the fastener in the hole the nut is centered in the coring.  Remove the fastener and thoroughly coat the machine bolt with wax so resin cannot stick to it but not on the nut.  Pour resin into the hole until almost full and insert the bolt/nut combination into the hole.  If you can insert them through the leaning post base then the holes, that would be even better as the alignment would be correct.  Just put some tape on the bottom of the leaning post supports so it can be removed once the resin sets up.  By using the nail to open the cells in the coring, you have increased the surface area the nut will be exerting force over.

I honestly do not know how well Azek will perform as a coring material.  My concern is that, like all coring materials, a layer or two of fiberglass is necessary on both top and bottom in order to have an I-beam structure that will not flex when walked on.  Just attaching the top skin to the Azek will not be enough to keep if from flexing a lot; you need that bottom glassed to complete the structure.  As to how well resin will bond to it, I would suggest buying a small piece from Lowes or HD and glass a piece of cloth to it then see how hard it is to pull it off once it sets up.

We were thinking of getting some cedar planks and using 5200 to attach the planks as added support. But I measured the coffin lid and it’s 1 inch from the top of the floor down to the inside support for the deck lid.with a 1” composite core I think it will be strong enough with the planking but maybe the AZEK will sit right on top of the tank

[Retainer]

I will use a small test piece first. The sign guy will bring me a small section to test.