Rear Berth Internal Gas Tank

[dbryceking]

So, I will start off with I am a long time Stalker of this site and first time poster. I have read several forums on internal gas tanks and I understand the pro's and cons. For me shifting the weight lower in the boat with a properly ventillated and plumbed tank is very appealing. It would free up cockpit space where my current 2, 12 gallon tanks are stored, for life jackets, tubes, foul weather equip, bumpers, and other light, wet, gear. It will also help calm the boat down in rougher water by lowering the CG. At least that is my thought on it. I am very impressed with the internal forward, 19gal bow tank that someone here installed and posted about. I also saw the square tank under the steering wheel console but, I like having my giant bed and don't want to loose that space. Last year me and my 3 kids took an adventure in my 26M for 10 days. We sailed/motored, ok mostly motored, from Norfolk VA up the Chesapeake Bay, through the C&D canal, down the Delaware Bay, and then up to NYC. You know kids they want to get there now, plus we were on a schedule as I only had limited leave days. We had planned on continuing the loop to Chicago except our motor died as we entered NYC. I am in the Navy and am currently deployed away from my boat so I have plenty of time to dream and come up with plenty of ideas. Since I can't just go out to my boat and measure, I thought I would ask you all for help. So with my style of sail a little bit and motor a lot bit, it is nice to have a lot of gas onboard.

I am looking at putting a Moller 19 gal rectangle tank in the aft end of the berthing, back where the starting battery sits now. The tank would run athwartships, just behind the mattress. Of course the battery would be moved forward. There are two tanks that I want to know if one of them would fit back there? 1 is a little wider but shorter(47.00L x 10.25W x 10.19H) 2 is a littler narrower but taller ( 58.00L x 6.00W x 14.75H). Its been a while since I have been in my boat but if I remember right there is some space by the battery well. Will the tank fit back there. Will it clear the steering linkage above? Additionally there will be the fittings and hoses comming out of the top of the tank.

The other thing I am concerned with a little bit is the 100-ish pounds of gas on a partially full tank sloshing back and forth athwartship. Though I have had my kids running around the boat and swinging from the main entry above the ladder, repeatedly, with no ill effects on the boat. Other than the S curve I am forced to steer.

As far as weight balanceing forward to aft, this is part of that process as I am really wanting to upgrade the boat and am trying to balance out all the stuff I want. (water tanks, 3 deep cycle batteries, forward v-berth gas tank, 115hp motor, blackwater tank, toilet, fridge, ect) So, before I can move on I was hoping someone could help me out with a quick look in their boat the next time they go out. Thanks in advance!

[Erik Hardtle]

Hi dbryceking,
I am one (maybe the only one) who did a bow gas tank. The biggest reason I did the bow, didn't even consider the aft, was weight at the aft. I usually sail with 2 -4 people and a 90hp motor and two gas tanks and the stuff I stow in the aft berth just made the back of the boat very heavy. I am still very happy with the bow tank. Here is a link to my website for the mod.

http://www.enctrader.com/hardtlefamily/ ... tm#bowtank

Good Luck,
Capt Erik, Admiral Jean, First Mate Christina & Swabbie Nicole
1999 MacGregor 26X, "KnotShore"
New Bern, NC

[dbryceking]

Erik, I agree with the Mac being stern heavy and I haven't even done my upgrades yet. When we were on the trip I would watch the speed climb every time the kids went up on the the bow. Also the bow would come down and she would just plane better. I also noticed that the more weight I put topside the more the boat rocked in the waves. I did have two 12 gallon tanks on the stern and bunch of crap in the aft berthing though. I figure that the more weight I can get lower in the boat, the better off I will be. My thoughts with adding weight have been to try and balance out everything I am adding. For instance, If I put 100# of water tank on the bow I need to offset that by 100# in the stern, ect... This is all based around what the 26M was designed for, 50hp with a 6 gal tank on the stern and a 200# person on the stern. So any major permanent weight that I add I am trying to distribute around that. <-- Hope that makes sense. I know that I want to do an internal fuel tank, add a 12 gal of water tanks, 3 deep cycle batteries, a refrigerator, a toilet with a waste tank, and a motor upgrade to a DF115. Since I haven't done any upgrades yet, and am still in the research phase I can put the stuff anywhere. With the gas tanks and plumbing them without hoses showing all over the cabin, I am stuck with the bow or the stern. I am potentially considering both, if the rear one would fit. Then I would be balanced with ~150# fwd and aft for gas & tank. I am thinking of sticking the deep cycle batteries and one water tank up in the bow in the V berthing storage area. I have the 26M with the galley built in behind the bathroom on the starboard side, not the slide version on the port side. So, once I add the toilet and fridge to the starboard side I will need to offset that weight with something on the port side. I can put water tanks or holding tanks on the port side. Basically, I am still just planning and wanted to know if the aft gas tank was even a possibility.

[Russ]

My vote would be for the way Erik did it. More weight in the bow seems to work better. These boats (at least mine) seems to be aft heavy.

Whatever you do, be careful and secure well, use quality fittings and hoses and ground the tank and fittings. You will need a blower if you put fuel below decks.

[Highlander]

If I went this route I,d do the aft center gas tank going front to back rather than p/s to s/b side fuel tanks usually have baffles built inside them to prevent fuel from sloshing around so make sure the tank u buy has them ! , kevin did this mod on his , aft mounted also means less length of fuel lines inside the cabin , less chance of air getting in the fuel lines causing fuel starvation issues , internally mounted fuel tanks need to be sealed in a box system with all internal fuel lines & vent lines sealed inside the box with no chance of spilled or leaking fuel entering the cabin this is much easier with the aft mounted tank do not vent into the cockpit area , vent into the top outside stern area same with tank fill - up just think about fumes on a hot summer day or enclosed full enclosure u should also think about a variable gas / fume alert mounted inside the cabin I have one , the one I have can have multiple sniffers this type would allow u to also have a sniffer in side the seal fuel tank box & cockpit area too if u wished this set up will tell u that u have an issue long before u could smell it , just don,t eat a lot of baked beans LOL , sniffer in the sealed fuel tank box should be mounted externally allowing for seasonal cleaning & inspection & easy replacement if needed these can be checked & tested regularly by a test button on the main alert panel , check out Kevin,s aft tank mod it should give u some good idea of what u can do

J
PS forgot to mention I also have a blower system mounted in my cabin, I would also mount one in the fuel tank sealed box if I done this mod , pretty sure u will need one blower at least just check reg for where it needs to be mounted , either way I would go with both blower systems

[aviro]

hi
I made this mod 2 years ago. 27 gas tank below the cockpit, just at the front of the rudder linkage, just great,
more stability and storage place under the seats, good double bed size highly recommended.
I install a Moeller Permanent Below Deck Fuel Tank 27 Gallon - 32627
see you
Jean-Francois

[dbryceking]

Aviro, I am intrigued by the 27gal tank that you installed on your Mac. Do you have any photos of the mod? How is the tank situated in the rear berth, fore and aft splitting the bed in two, or pushed against the back wall going athwartship? Do you sleep sideways on the bed now or can you still lay with your head pointed towards the bow. How did you strap the tank down? Where did you install the vent and fill ports? Any and all information on this mod would be greatly appreciated!

[kmclemore]

From a previous topic posted long ago...

I have a poly 18 gallon tank installed directly beneath the aft portion of the cockpit, in the center of the aft berth. There is an enclosure around it and it is vented to the outside air.

We never use that area for anything anyway - too hard to get to - and besides, it keeps my two sons from invading each other's "space", too!

You can see it in this picture:


Fill for the tank may be seen on the cockpit sole, just aft of the pedestal.


Leaves the two lockers free for holding propane bottles, the kid's deflated water toys, etc.

I should note that another Mac, "Windarra", has the identical tank setup as I do, although mine has more better ventilation, IMHO.)

[Tomfoolery]

Is an electric bilge blower required for that enclosure, since there's no engine in there too?

[kmclemore]

Is an electric bilge blower required for that enclosure, since there's no engine in there too?

I don't believe it's required, but it's a very good idea.

[dbryceking]

Thanks for the replies everyone. They all look really nice and almost like what I want on my boat. So from what I can tell, at least 3 people have added tanks to the rear berth and all 3 have different tanks. Jean-Francois has a 27gal, KcMclemore has a 18gal, and the "Windarra" has a 12gal. I am assuming that you all mounted your tanks directely ontop of the the water ballast tank. How did you secure the fuel tank? How did you support the rear bed after you cut the hole in the fiberglass bed support.

Do you think that I could mount a Moller marine 12 gallon tank (24.50"L x 18.50"W x 7.25"H) under the rear berth? There is also the 18 gallon and 25 gallon tanks with the same dimensions only longer 36" and 47" respectfully. I have seen mods with water bladders under there, "Southern Star". <--No, I am not even remotely thinking about a fuel bladder, just about the space that is available. I cannot remember how far the ribs are apart, or if they narrow as they go forward. Additionally I do not know how deep the space is below the rear berth inbetween the ribs and if it is a constant depth as you go forward. The tank fittings would be at the back of the tank, 2in from the back, towards the rear of the boat. This would easily accomodate fittings for tank filling, venting, ect... I would be willing to raise the bed a few inches to accomodate if it meant that I could keep the fuel tank hidden from view and still have the entire bed available for use.

Thoughts?

[dreamer]

I was thinking of one of those tanks last year the 18 gallons actually. I remember that the space under the mattress was less than 7.25 inches so you would have to create a higher floor maybe ( 3inches)for the tank to fit underneath it. As one goes further aft the space under the mattress becomes shallower. This tank would really put most of the weight of the gasoline down low.

[Highlander]

Not sure how the skipper,s who done this mod mounted the fuel tanks , but if I was going to do it ,I think I would make a sub floor that would be bolted down on top of the aft berth bed base , I would not want the fuel tank sitting on the bottom of the hull between the ballast tank channels there,s a lot of hull flex there to chanffer through a plastic fuel tank plus the shock loads on it @ high speed & a SS fuel tank could make a hole in the hull going the other way Just my thoughts on that idea , based on long term usage

J