Fuel Tank Mod

[bbelongie]

I'd like to move the fuel tank on our 2003 R21, (NON-EC), from its present location just aft of the engine to the stern locker. Aside of extending the fuel lines and purging out the air, are there any other issues that the longer fuel runs might create?
The reason I want to do this is so that I can replace the single house battery with a set of 6v SeaGel batteries in series to give me 180 AH storage. Both my wife and I require a C-PAP machine due to sleep Apnea. Our new machines draw about 2amps with the humidifiers off. (since we are on water, humidifiers are the last thing we need!) Along with our lights and a small fan for nights on the delta, we anticipate a total usage of 30-40AH for a night. The recommended draw down of a Gel or AGM battery is 25% of total AH capacity so I think we are OK there.
The other issue is replacing the existing alternator with a heavier unit, 50-70 Amp output so that the batteries will recharge within 4-6 hours. So far the numbers seem OK, but do I need to also replace the battery isolator/combiner because of the increased current? Any experts out there? I also intend to replace the Guest 6A shore power charger with a 30A unit.
My alternative is to use a Honda EU2000 generator to charge the Gel batteries, which means carrying GAS for the durned thing and putting up with it buzzing away back there.
Thanks!
Bob B.

 

[SlackwaterJack]

I can't speak with much authority as far as the capacity of the isolater/combiner or alt output needs go, but...Last year I moved my '05 R-21's fuel tank from it's spot under the engine cover into the rear lazarette. I have had absolutely, positively NO fuel issues with the extended fuel lines. The battery holder re-locates perfectly where the fuel tank used to be I just needed to move the small coolant recovery tank to the other side of its standard mounting spot ( I was even able to use the original holes).
The main reason I moved the fuel tank was so I could access the packing gland, coolant intake valve, and bilge pump without removing the batteries all the time. The move has worked out great and gave me a huge amount of room for tool boxes etc...I have had no real reduction in storage space in the rear lazarette either, as the tank fits perfectly into the area that's already restricted by other hoses (exhaust, etc).
I have a couple of pictures of the moved tank in my gallery as well as some diagrams that may help you. I have also recieved some excellent pictures from fellow Tugnut, Eric Fisher(Tugger Toy). He and I did the same mod at the same time (we compared notes for the project). I'm going to post them in my gallery as well ( I'll admit it...his pictures are better than mine). The pics are in the photos section under "Slackwaterjack" in a folder named "changes".
Hope it helps.

 

[rt11002003]

A couple of observations.

Does it make sense to go to a gel battery to get increased storage capacity if one is only going to use 25% of that capacity? Wet cells (and m/b others) generally recommend using no more than 50% of capacity. 25% of the 180 amp hr is 45 amp hr; 50% of a 120 amp hr would be 60 amp hr. 15 amp hr would be 33% more usable capacity.

A solar panel can be helpful in keeping the battery charged.

An increased output alternator may be helpful, but one would need to know the charging characteristics of the battery. Some batteries might not like a higher rate of charge. The regulator would actually determine the charge rate; the alternator determines the max amount available.

In that same vein, my experience with chargers is that gel cells don't like high amp charge rates. Again, the battery's characteristics determine the max charging rate acceptable.

Gene

 

[tuggertoy]

My husband, Eric, also did the same mod on our 2006 Ranger 21. Eric and Alex (Slackwater Jack) had many conversations about this. The end result has been great. Eric also added 2 Raycor fuel filters in the rear compartment. I am sure Eric would also send photos if required.

Moria

 

[Andrew Custis]

I cannot comment on the fuel tank other then I do not see any issues with doing this at all. I will certainly steer you away from Gel Cel batteries. They are very sensitive just like Gene had said about charging characteristics. I personally think 6 volts are becoming a thing of the past with the newer AGM 12 volt batteries available. AGM are nice because they can take a charge faster then a normal battery and hold a charge much longer then a lead acid battery.

I dont think you will have any issues with your current isolator that you have installed. Can you get me the model number?

 

[tuggertoy]

Hi Bob,

As Slackwaterjack (Alex) mentioned earlier in this post we both worked through this modification together last Fall.

When we bought Tugger Toy last August, the previous owner had already moved the batteries from under the hood to the floor of the rear lazarette storage compartment, in order to gain better access to the stuffing box and the bilge pump. The new location placed the batteries just to the port side of the center line of the boat. The problem was that this basically reduced the usable storage in this compartment by more than 50% . After spending some time looking at the situation I had decided to move the batteries to the starboard side of the compartment, nestled between the exhaust hose and the bilge pump discharge hose, which is basically space that is not suited for storage anyway. Fortunately, Alex and I had already connected on Tugnuts and when I mentioned my thoughts to him he told me he was considering moving his fuel tank to the same location that I was considering for the batteries and the rest is history. As his fuel tank had less fuel in it than mine at the time he disconnected it from the factory location and test fit it in the new location. It fit! So together we worked out the details and have since both completed our modifications. My wife and I have logged about 30 hours with the new setup and have found no issues to date. I chose to plumb a twin Raycor primary fuel filter manifold at the same time, and installed it along with the new fuel lines. It is plumbed in parallel so that only one filter is at work at a time but if it should become fouled I can change over to the other filter without having to reprime the lines. After moving the tank aft, I moved the batteries forward, under the hood again and as Alex mentioned this now provides room for a few tool boxes, which are easily removed if access to the stuffing box or bilge pump becomes necessary.

I just added a new album titled "Mods" which features some pics of the various changes described here. If you have any questions, please feel free to ask.

Eric

 

[bbelongie]

Thanks folks!
Real life done got in the way of my online and onwater time.
Andrew: I will have to take a picture of the combiner unit, it's a Guest, but only way to see the model number appears to be to remove all the wires...not going there today, we're on the water Thursday.

As for the SeaGels, they are a year old and I am already invested in them, so I figure I'll get a controlled charger from West Marine, that way I can complain to them if the batts get fried.

All: thanks for the info on the tank, looks like I have a winter project...