Fuel Tank Update

[jibes138]

Last year my fuel tank sprung a leak, a very slight seepage, so I pumped it dry and while agonizing about how to remove it without boat surgery or engine removal I installed a small 6 gallon tank to keep me going. Well after months of procrastination I finally took SailingCal21's advice and did some quarterberth surgery and pulled out the old tank. Use of a Rockwell (Fein equivalent) vibrating tool made the work a breeze. I am now waiting on new control cables for the engine that I need to install first, then rebuild the tank support structure that had some rot and to fit the new tank of slightly different dimensions.
I decided to go with a rotomolded tank of slightly smaller capacity (old was 30 gal, new is 23 gal.) that I can pull in and out easily for cleaning or replacement if ever necessary. The new tank is 24 x 20 x 12, while the old tank had an angled bottom and was 23 x 22 with 17 high in the front and 12 high in the back. So eliminating the 17 dimension makes the tank removable without a problem. If I keep the small tank as a day tank I gain back the capacity lost by the smaller main tank.
While screwing around with the control cables to measure lengths I found one pedestal mount screw was loose and leaking, thus the rotted wood and the corrosion of the tank. A little butyl tape should seal it right up.
I am impressed with the new tank for the money, 208 bucks and it came with a cleanout port already installed that was not part of the specifications or in the photos of the tank on the web sites. The angled fill and vent align right with where the old ones were so installation should be easy for those items.
I need to add a diesel return sender unit that will add another 45 bucks to the cost, but overall pretty inexpensive.
Here's some pictures of the two tanks and a close up of the holes created by the corrosion. I'll post some shots of the tank installation at a later date. I also picked up a Racor 500MA to keep the fuel in good shape and I'll use the old filter a Racor 120S as a bench filter to polish fuel before I put it in the new tank. I fill it with 5 gallon jugs so I can polish in the garage then put good clean fuel in the boat tank to start with. The old tank (28 years) had a lot of black nasty looking stuff on the bottom but the inside walls looked sparkling clean.
Many thanks to SalingCal and Dave Mauney for their advice in this process.

 

[damauney]

Dave

Nice job. Glad I could help. SailingCal also gave me the encouragement to replace tank. I noticed originally that there was a screw through the bottom of a vertical member for the fuel pump mount in the front of the old tank. When I removed that member I noticed that a screw holding vertical piece stuck right in tank where your largest pit is. Warning for O'Day 34/35 owners to check this vertical member attachment points and tank.

My tank cradle was also rotten because of leaks from pedestal base. I believe SailingCal had the same problem. In my case I took the pedestal off and found soft filler like bondo. I ended up digging it all out putting in glass build up on it's place, gel coating, butyl rubber (thanks Maine) and reinstalling pedestal. No leaks now. It appeared pedestal moved before in heavy weather. Wonder why.

Goodwinds
DaveM

 

[SailingCal21]

Glad that I was able to blaze a trail.

Ya'll were way luckier than I. I had to replace the sole board by laminating two pieces of marine plywood and epoxying in place. O'Day had fiberglassed the wood in place which made a nice enclosure to retain the moisture plus hide the effects of the leak. I decided to leave the wood exposed so that I could monitor any new leaks.

Wish I had room for an inspection/clean-out port like you were able to do Jibes. Turns out that I'm only using about 12 gallons a season so less capacity would not have been a problem.

 

[jibes138]

An option to consider

Glad that I was able to blaze a trail.

Wish I had room for an inspection/clean-out port like you were able to do Jibes. Turns out that I'm only using about 12 gallons a season so less capacity would not have been a problem.

I sent these pics to DaveM previously but they might be worth consideration. I put in a small 6 gallon tank in the port cockpit locker. I am contemplating leaving it and using it as the main draw for daily running and then fill it up from the main tank using the electric fuel pump. All the fuel going in the small tank will go through the Racor 500MA first. Kind of like a really simple polishing system with just 2 valves. One valve after the pump and one valve in the return line. The small tank is advertised at 7 gallons but I could only get about 6 gallons in it. Still half a year's worth at your usage rate.

I spent today designing the new cradle for the flat tank then buying the materials and building it. I have all the pieces cut and sanded and plan to epoxy all the wood tomorrow. Rather than marine ply I am using pressure treated plywood which should be plenty strong enough and with epoxy coating should work fine. I'll send some pics when done. Also I created a set of assembly and detail drawings for the cradle. I don't have a CAD program so I did them by hand but can scan them if anyone wants them. I'm not sure how exact the angle will match the hull but I plan to have a slight forward lean to the tank so any crud will settle in the front, the pickup tube is about in the middle on the port side of the tank. I assume I'll be doing some shimming at installation.

I plan to increase the size of that vertical board that the pump mounts on so I can also mount my new Racor. I hope it will fit with the battery in the OEM location. Stay tuned.

 

[damauney]

SailingCal

I too had to replace the whole plywood under cockpit sole as well as re-core part of the cockpit sole while I was redoing the pedestal base. I think the soft pedestal base was the cause of the whole problem for me.

Goodwinds
DaveM

 

[SailingCal21]

Thanks for the pics. Good idea to have a "day tank" arrangement with on board polishing for weekend and day sailing.

Your port locker is way too clean... or perhaps mine is way to junked up?

 

[jbowersett]

My 34 is 31 years old and still has the original fuel tank, so I feel that I'm living on borrowed time as regards leaks. When the time comes, I would love to be able do the job without cutting new/bigger holes anywhere.
I like what Jibes has done by installing a smaller molded tank. Could that tank be installed without cutting any fiberglass? Which begs the question, have any of you 34/35 owners tried cutting the old tank in half with a sawzall to get it out without cutting fiberglass? Finally, who is the manufacturer of the molded tank shown in Jibes pictures?

 

[damauney]

I cut my tank in half in the horizontal plane with a sawsall after empting it and blowing air in the fuel sender hole and out the fuel fill for a month with a 12 volt muffin fan just to make sure it was dried out and fumes were gone. Can then get it out quarter birth with no glass cutting. Put 20 gal tank back with same geometry just shorter. Only had to cut a 1.5 X 13 area out of glass to get new aluminum in. Can provide more detail if you want it.

Goodwinds
DaveM

 

[jibes138]

Moeller makes the small tank I installed, and I bought it through OceanLink in Rhode Island. I have since seen it advertised on the West Marine website as a "test tank" so you can check it out there. They claim it is a 7 gallon tank but I only got about 5 gallons in it and it could probably take another half to one gallon to be full right to the top. It is one foot cubed, so 12 inches on each side. A one foot cube is about 7.5 gallons or so. But the wall thickness is 0.200 so the interior volume is less than advertised. Also the plastic is not perfectly rigid so the sides bow in a bit making the interior further smaller. No cutting involved with my installation, I drilled holes for the hold down straps and put good fender washers under the screws so it doesn't go anywhere, I debated putting in a wood frame but was just trying to get through hurricane season with the tank until I did a bigger replacement.
Moeller is about the only source for plastic tanks these days from what I can see, EPA rules must have scared others away.
I plan to use two teak trim boards to re-install the piece I cut out of the quarterberth, and use a plywood backing plate that will be invisible. I will seal the cut joint with something like 3M 4000 so it doesn't rattle around and keep the engine compartment noise and smell somewhat isolated. I do not intend to glass it back in or screw around with gel coat. The only cut lines that should be visible will be the vertical ones and I doubt they will be noticeable since they are really narrow, time will tell.
I've got the tank cradle all epoxy coated, need to do a little finish sanding and then off to the boat to fit and install it. As I noted I expect some shimming to match the contour of the boat hull to the bottom of the cradle, the new tank will sit on four transverse slats of 1/2 PT plywood that are screwed down to four PT 2x6's cut to the fore and aft angle of the hull. The new tank will be far better supported than the old tank. The cradle will be tabbed to the hull on the port side and screwed to the back and starboard side of the old cradle. The front I intend to make removable so I can unscrew it and pull the new tank out for cleaning or replacement. I should have some more pictures from the boat by end of the week. I need to cut out the port side of the old cradle and the tabbing and sand it smooth before fitting the new cradle. This oscillating tool is a miracle tool for this kind of work. I will also need to plumb it all up with new hoses and clamps, but it should be a lot cleaner than the OEM set up.

 

[jbowersett]

Thanks Guys,
I'll keep all of this info handy for the day in the distant (I hope) future when replacement is necessary.
JB

 

[SailingCal21]

Based on the failure mode of the tank, you will have to replace your's in the near future. Let's face it 30+ years is a long time.

There is a chronic leak from the cockpit sole at the point where the Edson pedestal mounts. The leak is over the forward leading edge tank mount which keeps the wooden tray wet that is the source of corrosion. The corrosion area is not easily inspected without removing the batteries.

jbowersett, You can easily inspect for the leak however without removing the batteries. Access the engine compartment from the port side, look up and inspect the pedestal guard mounting bolts and that area. If it's moldy, wet or moist you've got the leak. On Karma the cockpit sole was reinforced in that area with plywood that was glassed in which made a nice tray to collect water plus hide the deterioration of the plywood for about 25 years. Both DaveM and I had to replace that board.

Here's what Karma's looked like, pretty obvious once you know what to look for:

 

[jibes138]

Tank cradle update

I finished sanding, epoxy, and re-sanding and assembly of the cradle to the point where it is ready to go in the boat. The starboard side will be the side from the old cradle still in the boat. The back will have a board added to extend the width by screwing it to the existing back of the old cradle. Here's some pics.

 

[SailingCal21]

Pretty stout mount. That ought to hold it. Looks tall to me, are you sure that you have the clearance to slide the tank over the side?

 

[jibes138]

The original tank had 4.75 inches of support all around the sides. So I kept that the same. Since it no longer has the angled bottom the side does come up a lot higher than before to engage the tank. I intend to have the front slide down between the battery tray and the cradle 2x6's and then screw it to both sides. That way I can slide the tank in place then screw on the front. To pull the tank out I just unscrew it and slide it out. It is 12 inches tall so it will be the same height as the old tank, since the old tank fit under the steering sheaves it should slide right in, the sheaves were in the way on the old tank since it had to be lifted up to clear the battery tray.
I haven't fit this in the boat yet so I could be in for a surprise or two, I'll let you know, but from my measurements it looked like I had plenty of room on the port side for the added width. I may try to find a metal 90 degree angle piece to wrap around each corner of the front so it isn't just a couple short wood screws holding it in. I will also have good hold down straps to hold the tank in place.
I will bring my saws and other tools and am prepared to perform surgery on the cradle if necessary right at the dock. I plan to work on it tomorrow but first I have to replace my engine control cables. That looks like a PIA snaking them into the pedestal, time will tell.

 

[Tom Potter]

Nice work Jibes, you need to hurry and get it put back together so you can steam over to Belhaven and sail in the Pirates on the Pungo regatta in a couple weeks.

 

[jibes138]

Installation progress

As expected I spent a lot of time in fitting the new tank cradle to the shape of the boat and glassing it in place. I planned to use the existing starboard side but after further inspection decided it needed to be replaced so I cut a new one and then epoxied it. Unfortunately epoxy takes time to cure so it slowed me down some.

A good lesson learned was using a Rockwell oscillating tool to shape support blocks to the shape of the hull under key cradle locations to properly support the tank and spread the loads into the hull. These tools can turn you into an artist.

Current status is the cradle is in and glassed to the hull, support blocks are under the cradle and epoxied to the hull. Rubber strips bonded to the cradle with 5200 for the tank to sit on, tank is in place and ready for plumbing. I made a new pump mounting board equivalent to the old one and the clamping plate and have epoxied those. The tank hold down straps I bought at Satan's marine supply store are too short, so I went to Lowes and got a 4 pack of tie down straps and cut the webbing off them and then sewed the webbing to the fitting from the tank hold down straps. only 12 bucks for (4) 10 foot long hold down straps.

I still need to figure out where to mount the Racor 500MA filter. I am considering inside the cockpit locker where the front is reinforced with wood and it gives plenty of room for filter changes and to monitor status and drain off any water or contaminants.

Here's a few pictures of the tank installed.