FibreGlass Holding tank?

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Sep 9, 2007
17
- - Sidney
Peggy I have posted a question on the Hunter site about this, but thought I should ask your advice too. I am thinking of making a custom-formed fiberglass tank (gelcoat on the INSIDE to seal it) to replace an aluminum one in a hard-to-get to location on my Vision-32 (the dirty job of removing the tank from below the transom step has already been done). By making a plaster mold I think I can fit a 12 gal tank through the 10x14 swim step hatch without having to cut any of the transom glass. My questions for you is : are there any problems in using a fibreglass tank? Or am I better off to plumb two Ronco 6 gal tanks together as Rick Dinon outlined in an archived post ? Thanks Mike
 
Sep 9, 2007
17
- - Sidney
Peggy I have posted a question on the Hunter site about this, but thought I should ask your advice too. I am thinking of making a custom-formed fiberglass tank (gelcoat on the INSIDE to seal it) to replace an aluminum one in a hard-to-get to location on my Vision-32 (the dirty job of removing the tank from below the transom step has already been done). By making a plaster mold I think I can fit a 12 gal tank through the 10x14 swim step hatch without having to cut any of the transom glass. My questions for you is : are there any problems in using a fibreglass tank? Or am I better off to plumb two Ronco 6 gal tanks together as Rick Dinon outlined in an archived post ? Thanks Mike
 
Dec 8, 2007
478
Irwin 41 CC Ketch LaConner WA
My 2 cents

Both my water tanks and my fuel tanks on my Irwin 41 are fiberglass built in during boat construction. So I dont know why not. Just do a first rate job of building it. Are you planning on haveing a gasgeted inspection port? If so you might consider a comercially made port so the flange is good and true for sealing purpose. That is the only area of my fuel tanks that have had any problums with a little weep.( had it fixed so hopfully no more ) The boat is 25 years old. No other problums. Nigel Colder thinks they are the best, could not get his boat builder on his new boat to go with the idea due to labor cost. ( Production boat not a one off ) By building the tanks when you build the boat you can use irregular shaped unusibal area normaly wasted, and get the tankage as low as possibal in the boat where it should be. PS: I put 1000 to 1700 gal fiberglass Septic tanks in the ground all the time. If they leaked EPA would not allow them.
 
Dec 8, 2007
478
Irwin 41 CC Ketch LaConner WA
My 2 cents

Both my water tanks and my fuel tanks on my Irwin 41 are fiberglass built in during boat construction. So I dont know why not. Just do a first rate job of building it. Are you planning on haveing a gasgeted inspection port? If so you might consider a comercially made port so the flange is good and true for sealing purpose. That is the only area of my fuel tanks that have had any problums with a little weep.( had it fixed so hopfully no more ) The boat is 25 years old. No other problums. Nigel Colder thinks they are the best, could not get his boat builder on his new boat to go with the idea due to labor cost. ( Production boat not a one off ) By building the tanks when you build the boat you can use irregular shaped unusibal area normaly wasted, and get the tankage as low as possibal in the boat where it should be. PS: I put 1000 to 1700 gal fiberglass Septic tanks in the ground all the time. If they leaked EPA would not allow them.
 
Dec 2, 1997
8,958
- - LIttle Rock
Biggest issue is tank location

It's waaaay too far from the toilet. With a little effort, I bet we can find a location closer to the toilet that will make it much easier to install and maintain a tank. Edit: It appears from a reply to your same post in another forum that someone else has already found a much better location. If you want to build one out of fiberglass, go for it. But there are plastic tank suppliers both here and in OZ (assuming that your home port of Sidney IS in OZ) who offer non-rectangular tanks in enough shapes and sizes to meet your needs.
 
Dec 2, 1997
8,958
- - LIttle Rock
Biggest issue is tank location

It's waaaay too far from the toilet. With a little effort, I bet we can find a location closer to the toilet that will make it much easier to install and maintain a tank. Edit: It appears from a reply to your same post in another forum that someone else has already found a much better location. If you want to build one out of fiberglass, go for it. But there are plastic tank suppliers both here and in OZ (assuming that your home port of Sidney IS in OZ) who offer non-rectangular tanks in enough shapes and sizes to meet your needs.
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
mike, from down under, As peggie says try to find a location much closer

to the head. If you can fit it into the bilge, even better ! I built all of the tanks on my boat. No gel coat, just resin rich chopped strand mat laid up on a smooth mold then several plies of woven cloth and CSM. Molded in the fittings, added inspection ports, put them in place and tabbed them in.
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
mike, from down under, As peggie says try to find a location much closer

to the head. If you can fit it into the bilge, even better ! I built all of the tanks on my boat. No gel coat, just resin rich chopped strand mat laid up on a smooth mold then several plies of woven cloth and CSM. Molded in the fittings, added inspection ports, put them in place and tabbed them in.
 
Sep 9, 2007
17
- - Sidney
Too far??

Putting it under the swim step is pretty much the same as the factory location under the transom -- about 6' from the head. The other location that could be considered is below the stbd aft berth floor boards. This would reduce the distance from the head (on the other side of the berth bulkhead) to the tank to something between 12" and 18" (I'm guessing -- it may be less). However this involves cutting the fibreglass liner floor board a bit and making a rather thin double taper tank. The distance between the floor board and hull slopes from a max of 2" at the stern end to 10" at the head end over a 49" length. There is an additional thwartwise slope that limits the depth even more. So in addition to having to cut the liner/floorboard (of course this can be patched after), I would have to fabricate a rather long flat tank to get the volume up to about 12 gal. So how important is that distance? In your post Peggy, there is a reference to a reply in another forum .. where? I couldn't find it. Thanks, Ross and Still Raining, for your encouragement on the Fiberglass idea. If I go this route, I will definitely put a commercial inspection port in. Any suggestions on size, material or supplier? Also any recommendations on the other fittings to install on the tank? BTW, I am in Sidney BC, and its still raining here too -- too bad I'm not in the downunder Sidney -- if I were, I would be out sailing instead of dreaming about it! Cheers Mike
 
Sep 9, 2007
17
- - Sidney
Too far??

Putting it under the swim step is pretty much the same as the factory location under the transom -- about 6' from the head. The other location that could be considered is below the stbd aft berth floor boards. This would reduce the distance from the head (on the other side of the berth bulkhead) to the tank to something between 12" and 18" (I'm guessing -- it may be less). However this involves cutting the fibreglass liner floor board a bit and making a rather thin double taper tank. The distance between the floor board and hull slopes from a max of 2" at the stern end to 10" at the head end over a 49" length. There is an additional thwartwise slope that limits the depth even more. So in addition to having to cut the liner/floorboard (of course this can be patched after), I would have to fabricate a rather long flat tank to get the volume up to about 12 gal. So how important is that distance? In your post Peggy, there is a reference to a reply in another forum .. where? I couldn't find it. Thanks, Ross and Still Raining, for your encouragement on the Fiberglass idea. If I go this route, I will definitely put a commercial inspection port in. Any suggestions on size, material or supplier? Also any recommendations on the other fittings to install on the tank? BTW, I am in Sidney BC, and its still raining here too -- too bad I'm not in the downunder Sidney -- if I were, I would be out sailing instead of dreaming about it! Cheers Mike
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Mike on the northwest coast, Remember that a cubic foot of

volume is only 7.5 gallons. so if you want a twelve gallon tank you will need to find a 2 cubic foot space. You won't want large flat panels because that is how you make drums. Excessively long tanks will slosh inside and if your ears work well ............... lots of thing to consider. 6 feet isn't too far, less is better but a basically straight hose run is best, elbows add effective length.
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Mike on the northwest coast, Remember that a cubic foot of

volume is only 7.5 gallons. so if you want a twelve gallon tank you will need to find a 2 cubic foot space. You won't want large flat panels because that is how you make drums. Excessively long tanks will slosh inside and if your ears work well ............... lots of thing to consider. 6 feet isn't too far, less is better but a basically straight hose run is best, elbows add effective length.
 
Dec 2, 1997
8,958
- - LIttle Rock
I don't like waste tanks under cabin soles

When it's that deeply buried, the vent line has to be too long, with too many bends, to have any hope of keeping the tank aerobic. Ideally the tank should be within 6' of the toilet (closer is better, but it's not necessary to put it right next to the toilet)...and close enough to the hull to allow the vent line to be short (3-4'), straight and reasonably horizontal--no more than a 45 degree rise. That' not always possible, but there are plenty of locations that will let you get close. How important is the distance from the toilet to the tank? 6' has been shown to be the max distance bowl contents will travel in the time that 99.999% of people will pump long enough or leave their finger on a flush button. If it doesn't get to the tank, it sits in the hose to permeate it. The "other forum" was posted to one the forums specific only to the Hunter site.
 
Dec 2, 1997
8,958
- - LIttle Rock
I don't like waste tanks under cabin soles

When it's that deeply buried, the vent line has to be too long, with too many bends, to have any hope of keeping the tank aerobic. Ideally the tank should be within 6' of the toilet (closer is better, but it's not necessary to put it right next to the toilet)...and close enough to the hull to allow the vent line to be short (3-4'), straight and reasonably horizontal--no more than a 45 degree rise. That' not always possible, but there are plenty of locations that will let you get close. How important is the distance from the toilet to the tank? 6' has been shown to be the max distance bowl contents will travel in the time that 99.999% of people will pump long enough or leave their finger on a flush button. If it doesn't get to the tank, it sits in the hose to permeate it. The "other forum" was posted to one the forums specific only to the Hunter site.
 
Sep 9, 2007
17
- - Sidney
It is a straight run

.. pretty much to the location under the swim step. In fact it is straighter than the original location (under the transom), and should have no sharp bends. I measure it again today, and the distance is indeed just under 6'. As to the vent line (or lines), that is no problem. I have pretty much decided against putting the tank under the floorboard as it also has the disadvantage noted by Ross - I would rather have soft music lull me to sleep at night than sloshing noises in a long flat tank under the bed! Cheers Mike
 
Sep 9, 2007
17
- - Sidney
It is a straight run

.. pretty much to the location under the swim step. In fact it is straighter than the original location (under the transom), and should have no sharp bends. I measure it again today, and the distance is indeed just under 6'. As to the vent line (or lines), that is no problem. I have pretty much decided against putting the tank under the floorboard as it also has the disadvantage noted by Ross - I would rather have soft music lull me to sleep at night than sloshing noises in a long flat tank under the bed! Cheers Mike
 
Sep 9, 2007
17
- - Sidney
Fibreglass questions to Ross and Still Raining

... The problem is that the tank volume I need is too large to fit through the hatch, so I need to either use two tanks or assemble the tank in place. I propose to make a tank in two halves and then re-assemble it in place. Does the following plan makes sense? 1. Build up a custom-fit plug out of slices of 2" styrofoam (so that each slice fits through hatch). This plug is a mockup of the final tank, before fittings etc are installed. Hold the slices together initially with tape and adjust the slices as necessary until the shape, size and location is ok. 2. Remove plug peice by peice and tape it back together outside the boat. Determine where to cut it into two peices so that each peice (top and bottom) can fit through the hatch. Make the cut and then make sure that the two halves do indeed fit through the hatch and can be reassembled in place. When satisfied, glue pieces back together to make a single plug. 3. Smooth coat the plug, seal and polish it. Apply Gelcoat. Then glass over entire plug. 4. Epoxy a 1/4"x1" strip of wood around the sectioning cut line (step 2) to act as a stiffener and to provide extra epoxy area for the later reassembly. 5. Recut the plug along the section line (table saw) to produce a top and bottom section. Remove the plug material (styrofoam). Install fittings on the top and bottom sections as required. Also mount Inspection port and add stiffening to the top and fitting areas as needed. 6. Epoxy a 1/2" lip around the bottom section (at the cut line) to increase the epoxy joint area and to help position the top and bottom sections during reassembly. THis lip and the extra thickness (step 4) should give both mechanicl strength and a good surface area for the bonding of the top and bottom. 7. Put bottom section in boat, and fasten in place as necessary (may not need much since it is a custom fit to double-sloped space. Perhaps a little urethane expanding foam will be adequate 8. Make sure top section fits well, then put epoxy bead on lower section face (and the lip of step 6) and join sections together. Wipe off excess epoxy. 9. After joint 8 is set, epoxy a layer of glass over the seam (8) as added precaution and seal. 10. Paint the tank and have a glass of rum and coke! Sound like a doable plan?
 
Sep 9, 2007
17
- - Sidney
Fibreglass questions to Ross and Still Raining

... The problem is that the tank volume I need is too large to fit through the hatch, so I need to either use two tanks or assemble the tank in place. I propose to make a tank in two halves and then re-assemble it in place. Does the following plan makes sense? 1. Build up a custom-fit plug out of slices of 2" styrofoam (so that each slice fits through hatch). This plug is a mockup of the final tank, before fittings etc are installed. Hold the slices together initially with tape and adjust the slices as necessary until the shape, size and location is ok. 2. Remove plug peice by peice and tape it back together outside the boat. Determine where to cut it into two peices so that each peice (top and bottom) can fit through the hatch. Make the cut and then make sure that the two halves do indeed fit through the hatch and can be reassembled in place. When satisfied, glue pieces back together to make a single plug. 3. Smooth coat the plug, seal and polish it. Apply Gelcoat. Then glass over entire plug. 4. Epoxy a 1/4"x1" strip of wood around the sectioning cut line (step 2) to act as a stiffener and to provide extra epoxy area for the later reassembly. 5. Recut the plug along the section line (table saw) to produce a top and bottom section. Remove the plug material (styrofoam). Install fittings on the top and bottom sections as required. Also mount Inspection port and add stiffening to the top and fitting areas as needed. 6. Epoxy a 1/2" lip around the bottom section (at the cut line) to increase the epoxy joint area and to help position the top and bottom sections during reassembly. THis lip and the extra thickness (step 4) should give both mechanicl strength and a good surface area for the bonding of the top and bottom. 7. Put bottom section in boat, and fasten in place as necessary (may not need much since it is a custom fit to double-sloped space. Perhaps a little urethane expanding foam will be adequate 8. Make sure top section fits well, then put epoxy bead on lower section face (and the lip of step 6) and join sections together. Wipe off excess epoxy. 9. After joint 8 is set, epoxy a layer of glass over the seam (8) as added precaution and seal. 10. Paint the tank and have a glass of rum and coke! Sound like a doable plan?
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Seapuppet, I will study this when I am sober.

;D
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Seapuppet, I will study this when I am sober.

;D
 
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