1987 Chaparral 198C Owner - Difficulty of Aluminum Fuel Tank Swap?

[87Chappy]

Hi all,

I am New to the forum and boating! I recently got a 1987 Chaparral 198C cuddy cabin with an SEI 106 outdrive (likely swapped from the original Mercruiser Alpha One) and what appears to be a crate performance marine engine with thru hull exhaust.This was a boat my best friends dad bought new in 1987 and made a lot of customizations to it. I grew up on this boat (summers in northern MI) I’m excited to fix it up but new to the game, so I’m here for advice.

I need to replace the aluminum fuel tank (probably 48 gallons, original). I’d like to stick with aluminum for the new one. I’ll have to pull up the floor to get to it, which sounds like a project.

Has anyone swapped the tank on a similar ‘80s Chaparral cuddy?
- How hard is it to access/remove the tank? Tips for cutting/lifting the deck without wrecking it?
- What’s the swap process like? Any tight spots or tricky fittings to watch for?
- Pitfalls to avoid? I’m handy but new to boats.
- Where’d you get your aluminum tank? Looking at West Marine or custom fab—any recommendations?

Really would like to get this boat back on the water but not sure where to get a tank. Already have gone through and replaced lines and what not so I am sure it’s the tank. Last time I had it running I only put about 5 gallons of fuel to “test” if it was low or on the bottom of the tank and sure enough it leaked. Oddly the fuel was seen coming into the bilge area (if that sounds right) and then out where the drain plug would go (I was on land hooked to water muffs)

 

[SST]

Welcome aboard and happy to have an additional owner.

I own an 87 Chap 235XLC [Cuddy]. I have not replaced my tank. No leaks. But I did replace the filler pipe and modified the vent line. I didn't want to rip up the floor as was recommended by other owners. I didn't pull the old filler line out but relayed the new one therefore only cutting into the floor a little bit. So far so good.

I don't have any experience ripping up the whole floor. But there are others who will be chiming in shortly to help you out.

 

[Denny]

First off do not cover your girl tight, she needs all the fresh air she can get! You will loose your floor to get at your tank. If she is not a love item, and you do not plan on keeping her forever, along with money is not an issue, then prepare yourself for an adventure. If you have never done anything like this talk to someone who has. If you want to do it yourself, at least they can show you what you need to do, or maybe work with you.

I had to replace my vent and fill hoses.
I had help, and I hate the uncomfortable feel of fiberglass.

.

 

[Iggy]

Now Denny knows a lot more than me on replacing the tank. After all, he's done it. Plus, if there is any wood that needs to be replaced.

But I have heard of, cutting a hole in the tank and putting in a rubber bladder. On bigger boats this is not an uncommon thing to do

 

[Denny]

Now Denny knows a lot more than me on replacing the tank. After all, he's done it. Plus, if there is any wood that needs to be replaced.

But I have heard of, cutting a hole in the tank and putting in a rubber bladder. On bigger boats this is not an uncommon thing to do

Thanks for the info, I never knew that. Definitely something to consider.

 

[Iggy]

Thanks for the info, I never knew that. Definitely something to consider.

A few links. They are pricey, but whats the cost of cutting into your boat and the new tank?

https://atlinc.com/custom-fuelocker-marine-fuel-bladders.html

Ready Marine Fuel Bladders | Certified ISO 9001:2015 | USA

Marine fuel bladders provide temporary extra fuel storage on your boat or yacht to extend the range. Ideal for your next excursions or offshore fishing trip.

readycontainment.com

Marine Diesel Fuel Bladder Tanks – Collapsible pillow tanks & drums

Long range flexible tanks for ocean going yachts and motor vessels. Fits game fishing boats cockpit – Super Yachts decks. Double skin. Tank in a tank.

www.turtlepac.com

 

[87Chappy]

Thank you sharing the information and links. Still not sure what route I should take since the bladders are a bit more expensive than I thought they would be. Would the bladder itself go in the tank? Sorry if that is a dumb question.

 

[Iggy]

Thank you sharing the information and links. Still not sure what route I should take since the bladders are a bit more expensive than I thought they would be. Would the bladder itself go in the tank? Sorry if that is a dumb question.

Yes, it would. Pricy yes, but whats the cost of a new tank and the all the glass work. Generally speaking, you cut a hole in the top of the tank and insert the bladder. I would call them and get more info. Oh, and you need to dispose of the old tank.

 

[Denny]

Another thing you should consider, is there may be gas that is trapped in voids from the foam. I agree the bladder can be a good fix. But you have to clean up the mess that is left behind from the original tank. The gas that got on my foam did not dissolve the foam, however it was soaking wet, so I removed what was bad and replaced it with new spray foam. Spartan Chemical makes a product that will eliminate the left over gas on the foam and the odor. It is called Consume, it has microscopic bugs that will eliminate it, by eating it. I have used this product on many instances and it works creat. Basically how it works is, you mix it with a ratio of water pour it into the infected area and let it set for a period of time. Rinse it out and you are good to go.