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George D

2001 300 Signature fuel tank swap

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When I decided to tear into this project, I couldn't find anything specific online other than some tips from a user here who did one on a 27. This hopefully helps someone in the future.

I wasn't planning on making a tutorial so the pictures aren't very linear and I am going off memory from last year. I just have a few random pics as I went along. I am not a boat mechanic, just an industrious person with a lot of patience and a lot of tools. This job involves general mechanical disassembly, woodwork, fiberglass work, mild fabrication, and paint work.

I am going to do this in a few posts. 

 

The boat is a 2001 Chaparral 300 Signature with twin 5.0 Mercruisers and a 154 gallon tank. I bought it knowing it needed a tank, it had been sitting for over a year with the tank empty.

First off, make sure you don't have any gas fumes, you can easily blow yourself up. My tank had been empty for over a year and a half. I pulled the fill hose and could barely even smell fumes.

Despite that, I kept the fill and vent necks covered and sealed. Flushing the tank isn't a bad idea.

The issue with the aluminum tank is that if you have any water in the bilge, it corrodes the tank, typically where the rubber isolation straps are. In salt water, especially a marina, leaking stray voltage exacerbates the problem.

These are the tools you'll need. General hand tools: tape measure, screwdrivers, wrenches, sockets, razor scraper, flat paint scraper, small sledge hammer, large pry bars, small pry bars, small and large chisels.

Critical: You need a respirator, not a cheesy dustmask. You will be creating a lot of fiberglass dust and you will also be using spray adhesive in a confined space. Get safety glasses as well.

Power tools: extension cords, lights, sawzall, jigsaw, circular saw, drill, screw gun, angle grinder and most importantly,  a multi tool with lots of blades. I used the Milwaukee M18 cordless and it saved me tons of time. Photograph and label everything.

Before pic.4uto90ZwiIxykawKPNz4N92Hwf9sy20zhDHJCjYp

 

Phase 1:  Exposing the engine room side of the fuel tank.

Remove all the rear seating from the deck area including brackets Remove. all four floor panels and the aluminum support channel.

The first thing you need to do in the engine room is remove the batteries and battery cradles. I snap pics and then zip tie cable ends together. 

Remove the water heater and hoses,note the wiring. Remove the macerator, you'll have to cut the wires and reconnect them later. Remove the wooden dog house that protects the fillers. Remove the gas fill hose and gas vent hose from the forward part of the tank and seal the tank filler and vent with duct tape. Remove the wiring from the sending unit. Remove the gas feed lines from the engine.

Unscrew anything attached to the vertical wood panel at the rear of the tank, (fuel lines, cables, AC strainer). Unscrew the lower panel brackets from the hull and remove the panel.

Remove the fire suppression bottle from the firewall, unscrew all the cable clips holding the 110 V wires. I zip tied the wires in a bundle and strapped them up to the underside of the deck to keep them out of the way.

Carefully remove the silver faced foam insulation by rolling it towards the starboard side, I used a large flat scraper to keep it intact. You should be able to re-use this if you are careful.

 

Now comes the fun part. The deck you are standing on is two pieces of 3/4" marine plywood, stapled together with a few hundred air staples to create a 1 1/2" laminate deck , and then glassed into the hull on the front into the firewall and horizontally to the sides of the hull where the batteries sit.

I wasted a lot of time trying to be careful to save these two pieces of deck. Don't bother, they are going to get destroyed and using new plywood will be a much cleaner installation.

Use the multi tool to cut through the fiberglass where it meets the hull on each side, cutting horizontally from the outside towards the center of the boat, and then cut through where it meets the firewall by holding the saw vertically and cutting down.You don't want to damage the hull when cutting the sides, so go a little high, cut through enough to get a pry bar in there, you can always grind it flat later.  I ended up finding the seam between the top piece and the bottom piece of plywood on each side and cutting through it horizontally a bit,  then prying off the top deck first. I used chisels to split the laminate and help separate the fiberglass as well. Once you can get a bar in there, work your way around the perimeter and pry it up. Repeat with the bottom deck and pry it up. Its not easy, there are tons of air staples in it. Once you pry it up, be careful, its full of razor sharp staples.

 Congratulations! You are now looking at the tank!     Save the decks, you will need them to make templates for the new ones.

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Chipping and cutting fiberglass bonding the plywood to the hull.

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First deck popped loose, secondary deck still in place.

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Both decks out.

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Phase Two:  Aft Cabin Disassembly

Run an extension cord and a light down inside the cabin and get ready to remove the aft cabin. Make sure you have places to put all the stuff you're going to remove. I stacked it on the V berth bed and the dinette table.

You are going to need to remove all the cushions. The horizonontal ones are just popped in, a few others have brackets you can see, and then the ones on the back (firewall) are screwed in from the cushion side back. I honestly have no idea how they do this, but they are screwed from the plywood back of the cushion into the firewall. I ended up measuring where I thought the screws were and then drilling from the engine room side into the firewall and then popping the cushions off. You need to remove the curtain rail from the porthole, the privacy curtain, and any other trim that holds the headliner up. Once all the trim is out, start to unscrew the headliner. You need to cut the wires for the overhead light. Move all the parts to the bow.

Next, unbolt the mirror and carefully wrangle it out of the aft cabin, I didnt think it would come out, but it finally did.

Remove all the wooden slat brackets that hold the center bed cushions as well as the panels. You now need to start using a flat scraper and/or a razor scraper to roll the carpet back. Remove the carpet from the firewall and then start removing the floor carpet. I only pulled the floor carpet back to about 8" from the seam where the deck ends. I then used the same razor scraper to start working back the upholstery from each back corner of the cabin.

Now you should have the firewall exposed, and now you are going to cut a giant hole in it!

From the engine room side, use the tape measure to mark out how big the hole needs to be by using the stringer on the starboard side (pic below) as a mark and drilling a small hole at the bottom where you want to start your cut, and then do the same at the top. I believe the height was determined by where the deck cap sat, I went as high as I felt comfortable I could work. 

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On the port side, I went in the cabin and went as tight to the cabin wall as possible. Since I was going to be covering it, I just used a sawzall to cut the opening after starting it with the multi tool. Looking back, it may have been better to cut the fiberglass bonding the firewall to the side cabin wall and then removing that whole piece of plywood as opposed to having that 8" piece on the port side just sitting there.

 

The next part is the aft cabin floor. This is a little weird as you only have stringers on the starboard side and bow facing side. The port side goes under the head so you can't really get at it. I was going back and forth between cutting the floor flush with the wall or leaving a few inches. In hindsight, I should have cut it flush with the wall and then re-installed it with an L bracket, but I left a few inches and used a combo of L bracket and fiberglass. Jumping ahead with this pic, but its the only one I have showing the weird cabin wall arrangement.

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Once the floor is out, you can start unscrewing the tabs holding the tank in. I used a 1/4 ratchet drive with a phillips head. A lot of them were stripped so I had to use vice grips to turn them out, very tedious. Of course the tab that was blind, under the floor in the pic above, was totally stripped and I ended up just yanking the old tank until it broke off.

Once it was all unbolted, I grabbed the tank and wrestled it out and stood it up in the bilge. I laid old blankets over the transom to protect the seats and had a few friends help me load it into my truck, that it barely fit into (F150 short bed with toolbox).

Congrats on phase 2, your tank is out!  

 

 

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Phase 3: new tank and materials.

I had a new tank fabricated by Luther's Welding in Bristol, RI.  They duplicated the old tank but built it thicker, in 3/16th aluminum.

It is a thing of beauty, they did a great job. They leave the tab holes undrilled so you can match them to your hull.

 

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After I got the tank, I coated the bottom and sides with Glovit epoxy. I had also picked up a few sheets of 3/4 marine plywood for the engine room deck and I used the old engine room decks as templates.  I coated the bilge facing side of the plywood with Glovit.

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I also picked up 1/2 marine plywood for the aft cabin floor.

I went to Jamestown supply in Bristol, RI and told the clerk what i was doing. He spent the next 15 minutes walking me through the store getting everything I needed which was epoxy resin and hardener, sheets of fiberglass matt, a roll of matt for seams, silica for thickening the epoxy, a few fiberglass work tools, acetone, and a two part epoxy bilge paint.

I then went to Lowes to get some stainless hardware and some aluminum L brackets.

After drilling holes in the mounting tabs, I ran pieces of old garage door cable through them and used mini u-bolts to secure them into loops to use as handles. 

Back at the boat, I scrubbed the bilge out, re-secured the black plastic mounting cushions, and prepared to re-install the tank.

You need four people to lower the tank in, sort of like lowering a coffin into a grave except it needs to go in slightly cockeyed to get under the port corner of the aft cabin.

It takes a little persuading, but then it pops in. You can then start screwing it into the hull stringers, using new hardware and the 1/4 ratchet with extension.

Congrats! Your tank is in!

 

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Phase 4: Aft cabin deck and firewall rebuilding.

Now its time to button up the aft cabin.

This is the "totally open to interpretation" section where people will most likely do it differently than I did. I msyelf wouldn't even do it this way after having a chance to really look at the pics and reflect back. I used a combo of the old floor and new measurements to make a new floor. I really didn't trust the thin stringer face I had to work with so I decided to install aluminum brackets on the starboard side. I drilled and tapped the brackets and then used countersunk taper head machine screws.

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On the port side, I used another L bracket, mixed the epoxy to a peanut butter consistency and then used L brackets on the firewall. Once it was cured, I laid down multiple layers of fiberglass matte across the floor and then five layers on the seams, over the cured thickend epoxy. Looking back, I should have put an L bracket on the port side wall and cut the floor flush to the wall but my original design had 2 aluminum plates acting like a sandwich. I think if I was going to do this again, I would check into  just cutting the new piece of floor 3" oversize on each side and laying it over the old one. I don't think I would even notice the 1/2" under the cushions. 

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I kept laying in glass until i built the floor up to its orginal level.

 

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Once it was all cured, I sanded down any sharp spots, then used 3M spray adhesive to glue the carpet and upholstery back. For the rear cushions, I bought commercial grade velcro and attached them to the firewall, they are solid.

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Phase 5: Engine Room Deck

 

I laid the new plywood on sawhorses, then laid the old decks over each piece and marked them up with pencil. I made the main cuts with a circular saw and round cuts with a jigsaw.

I then screwed them in with stainless torx screws, God help the next poor soul that has to pull these decks up.

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I then added a new firewall over the old one, also in 3/4" marine plywood, that sits on top of the decking and adds a ton of strength. Probably a bit overkill, but i felt it tied everything together well.

 

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I then laid in layer upon layer of fiberglass matte on all the new deck to old deck seams, as well as deck to firewall seams, making it waterproof. I used a paint roller to coat all the wood with epoxy resin.

Once the glass cured, I smoothed any sharp spots then painted it with a 2 part matte epoxy that has a little tooth to it, adds a little no slip. I also relocated the water heater closer to the edge of the hull by bending the mounting tabs to conform to the hull shape contour. I never liked it where it was before. This frees up a lot of room to move and will also be a mounting area for my small dinghy outboard at some point.

 

I sprayed the 3M adhesive on the firewall and rolled the silver/black soundproofing back over.

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Phase 6:  Reassembly and final details.

I re-installed everything I took out in phase 1 and sea trialed it. Once I was happy with everything, I finished it up.

I bought some diamond plate rubber mat and glued it with 3M spray adhesive and then mounted stainless D-rings for my toolbox and generator. As with anything you are screwing through the deck, make sure the hardware isn't too long. Lst thing you need is a tank puncture.

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I launched it August of 17 and hauled out at the beginning of November with no issues.

It was a lot of work and I would probably do it a little differently if I had to do it again, but now I should be in good shape for a while. My plans before launching this year are to wall off the bilge with a dam to keep that errant inch or so of water from getting at the tank again.

 

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Thanks, hopefully this helps not only a Chap owner, but maybe keeps a yard that has never done one from having to pull two engines and the radar arch when it is totally unecessary. Removing the engines frees up very little room.

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31 minutes ago, George D said:

Thanks, hopefully this helps not only a Chap owner, but maybe keeps a yard that has never done one from having to pull two engines and the radar arch when it is totally unecessary. Removing the engines frees up very little room.

My '08 Sig 270 needed a gas tank replacement in 2012. It went back to the Chap assembly plant in Nashville, GA.  They removed the single engine and cut the floor of the aft cabin to access the tank. Since my boat is narrower than yours, perhaps that required the engine to be removed. 

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Great practical info! Thanks for sharing.

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Thanks a ton.  I like your comment on the video "a bigger project than I thought"  Aren't they all.  

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On 2/13/2018 at 1:23 PM, Roady68 said:

Thanks a ton.  I like your comment on the video "a bigger project than I thought"  Aren't they all.  

Indeed, but once I was that deep into it, there was no turning back. When I went to pull the tank, it got stuck, and I had a horrifying moment where I thought I was going to have to remove the stairs and and the head.  I almost gave up. Turns out, the tank is just really really heavy.

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On 2/13/2018 at 11:57 AM, MontreAl said:

My '08 Sig 270 needed a gas tank replacement in 2012. It went back to the Chap assembly plant in Nashville, GA.  They removed the single engine and cut the floor of the aft cabin to access the tank. Since my boat is narrower than yours, perhaps that required the engine to be removed. 

The Chap plant would know better than anyone on the 27, but I talked to another 2001 300 Sig owner that paid a fortune to have the radar arch and engines removed to do a tank swap. Before I embarked on this, I had a few shops give me prices and they all wanted to pull the engines and arch. Prior to owning this boat, I had a Monterey 27 that needed a tank. Same thing, everyone wanted to pull the engine. I contacted Monterey and the rep sent me step by step illustrated instructions on removing the tank with the engine in. Monterey actually designed the boat with removable panels to swap the tank, I didn't have to cut a thing.

When I contacted Chaparral, they offered no help whatsoever. Basically told me to find a local boat yard.

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On 2/26/2018 at 10:30 AM, turbotank said:

George, Did you get a picture of the tank model number tag? 

I still have the tank, its in my back yard, but I have the blueprints for it as well if you need them.

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George, thanks for this post! I may have the misfortune of needing to do the same thing, I'm not sure yet. I just went to my 2003 Sig 300 at  the boatyard briefly yesterday to start the commissioning process and there's a strong smell of fuel in the bilge. So, I left one of the engine covers open and the door in the shrink wrap open a bit to air it out. I have to go back soon to take off the wrap and check things further. I'm hoping it's just a spill from winterizing, but that may be wishful thinking.  If not, your post of the replacement process may be very helpful!

Do you happen to know if the 2003 uses the same tank as your 2001?

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I don't know for sure, but the 01 looks just like the 03. If you need the blueprint, I can email it to you.

 

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I think 1998 to 2003 are the same boat design.  I think only change was the radar arch changed from backward leaning to forward leaning somewhere around 2001 model year.  I believe, but don't have enough details, that the 2004 Signature 29 is the same hull layout.  Cockpit is similar too, but aft cabin is different.  

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On 2/26/2018 at 10:30 AM, turbotank said:

George, Did you get a picture of the tank model number tag? 

The number of the original tank is 29006-1600153921

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