Replacing a fuel tank

Jokani

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On the last trip of the 2015 season the original mild steel fuel tank on my Westerly Centaur developed a leak, and dumped most of it's contents in to the bilge, luckily there was just enough diesel below the source of the leak to get me back to a harbour.

So I need a new tank!

Tek Tanks sell one:

tek-tanks-westerly-centaur-fuel-tank.png




The tank is the same size as the original Westerly one, but the fittings could be for any engine setup.

I will be connecting the tank to a newly installed VP MD2020, so I think I need

1 x 38mm hosetail for the filler
1 x 8mm hosetail for the fuel return

But there are a few things that I am unsure of:

  1. Do I need to vent the tanks to a thru-hull? I see that some installations have vents but I'm unsure why, certainly Westerly did not fit one to this Centaur, but I'm not sure if now having a return pipe changes that?
  2. The MD2020 has connections for 8mm ID fuel pipe, so I presume I can use 8mm ID diesel rubber pipe throughout the installation, including the tap and return
  3. It is only a short distance form the tap to the fuel filter, would it be sufficient to use diesel approved fuel pipe rather than copper pipe?
  4. The old tank did not have an inspection hatch, I think I can save money and not spec one for the replacement?
  5. There is plenty of room, so I may increase the width from 370mm to 500mm and increase the capacity/range. The new engine is half the weight of the old so I presume increasing the size of the tank/weight of fuel would not be an issue?

Thanks in advance for your advice.
 

PetiteFleur

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Have you considered an off the shelf fuel tank? There may be one that will fit your space and it will be a LOT cheaper. I believe Tektanks also do an off the shelf range, also look at Plastimo, Vetus and Osculati. Also look at CakTanks who specialise in motorhomes but again they may have one to suit your space. Most of them have inspection hatches and spaces for fuel gauges, return pipes and vents - it is certainly recommended to have a vent, mine vents into the cockpit. Just remembered there is a place just outside Ipswich that also does fabricated tanks but cheaper than tektanks. I'll see if I can find their details. Found it -
It's stansa.co.uk Good Luck!
 
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VicS

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Have you considered an off the shelf fuel tank? There may be one that will fit your space and it will be a LOT cheaper. I believe Tektanks also do an off the shelf range, also look at Plastimo, Vetus and Osculati. Also look at CakTanks who specialise in motorhomes but again they may have one to suit your space. Most of them have inspection hatches and spaces for fuel gauges, return pipes and vents - it is certainly recommended to have a vent, mine vents into the cockpit. Just remembered there is a place just outside Ipswich that also does fabricated tanks but cheaper than tektanks. I'll see if I can find their details. Found it -
It's stansa.co.uk Good Luck!

You must have a vent to let air into the tank as you pump the fuel out.

The Berwick I used to sail just had a small plastic pipe up inside the stern locker.
 

macd

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You must have a vent to let air into the tank as you pump the fuel out.

The Berwick I used to sail just had a small plastic pipe up inside the stern locker.

It's also possiby to buy filler caps with vents built-in, although a dedicated one is more usual. The topsides isn't the best place for it: somewhere dry, such as Vic's locker, is better. If you're worried about losing fuel through it when filling, fit a catch-bottle.

To the OP: I'd think long and hard before deciding against an inspection hatch. There seems to be a new thread every month from someone who wishes his tank had one. I'd also talk to Tek-Tank about ther fitting a (top exit) tank drain. Their regular take-off/inspection covers don't have one, but they certainly have plenty of experience of fitting them. "Do it right, do it once."
 

lw395

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I'd have the draw-off on the top of the tank, together with another one in case you install an eberbasto later.
Also a draw-off from the very bottom of the tank for removing water etc. Preferably drawing from a small sump.

Yes you need a vent.
Some tanks need a big vent to avoid splashback when filling.

Making tanks that fill nicely to the brim without anything getting belched back on to the deck seems to be a subtle art?

Instead of an inspection hatch, my old boat had a second filler on the top of the tank. Tis was adequate for cleaning, and was handy for adding fuel at sea from cans, FWIW.
 

PetiteFleur

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Pacermarine now seem to have a good selection of fuel tanks complete with inspection hatch, space for a gauge, filler, vent, return etc. all at a very reasonable price - look on ebay and you'll see their range.
 

pvb

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It's a few years since I had my Centaur, but I seem to recall that the fuel tank is under the cockpit floor, isn't it? This effectively means that there's little point in having an inspection hatch in the tank as you won't be able to access it without major cockpit surgery or removal of the tank.

You do need a vent, so that air can get in to the tank to replace the diesel which is used.

For short runs, it's certainly OK to use rubber fuel hose rather than copper.

Trafalgar Yacht Services sell a replacement stainless tank for 395. This would be a straight swap so might be an easier proposition.
 
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Jokani

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Thanks for all the help and advise, I have made some enquires with the companies suggested, I'll report back on how I get on and hopefully post a picture if the final installation.
 

SiteSurfer

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I just replaced my fuel tank in a not disimilar boat to yours, I went for an off the shelf tank and it was suprisingly straight forward. (My original tank looked spookily like a metal version of the one you posted).

I note that your tank is/was gravity fed - something which I got sidetracked by until I found out it wasn't required on a more modern engine.
 

Jokani

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Thanks for all the advice, much of which I think I have incorporated in to the design of a new bespoke tank. Unless someone points out a major mistake in this design spec, this is what I will order:

fuel-tank-westerly-centaur.png


I looked at standard size tanks, but the space in a Centaur really requires a trapezoid shape to make the most of the space under the cockpit floor. I could have gone for a standard shape and saved money, but would have had to reduce the volume to fit. By going bespoke I can increase the volume by 35% for 38 litres to 58 litres. Also, it will fit exactly where the old one was without and additional work on my part.

Cost wise it is cheaper than Tek Tanks (who did not respond to two emails), and also the straight replacement from Trafalgar Yachts, even with the extra volume, Wema sender and guages, extra dip pipe and 90 degree elbows.

I decided to order from Terry at Henderson Plastics as he responded quickly to my emails, and they were the best value for money compared to other bespoke plastic tank quotes.
 

rogerthebodger

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I would incorporate as large bolt on access hatch just in case you need to get into it later. Inlets/outlets in a fixed section on one side of the top and the rest of the top removable.
 

sarabande

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you need at least two transverse internal baffles with limber holes to reduce sloshing around, and to provide a bit of extra structural strength. Nothing heavy, but to about 2/3rds of the way up the wall.


EDIT

and I'd add 4 say 15mm blocks on each top side, so that you can fix the tank down with decent straps or battens.
 
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rob2

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Whether the extra cost of a bespoke tank and its additional capacity is worthwhile to you will depend on your typical use of the engine. If you use it for most of the season just to get on and off your berth, then over capacity can be a curse - moreso now that most suppliers are adding bio-diesel. As the advice to prevent bug infestations is to keep the tank full, you will always be carrying too much fuel. If not used within a reasonable period the cetane rating will deteriorate causing loss of top end power and quite possibly starting problems in cold weather, especially if you have no pre-heaters. Of course, when you plan a summer cruise it is nice to set off with a quantity of fuel which would allow you to motor all the way if required and refuelling from a jerrican halfway across is not a pleasant occupation!

Rob.
 

pvb

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I would incorporate as large bolt on access hatch just in case you need to get into it later. Inlets/outlets in a fixed section on one side of the top and the rest of the top removable.

I can't see any point in having an inspection hatch, as the tank is directly under the cockpit floor, so to get at the inspection hatch you'd need to either take the tank out or take an angle grinder to the cockpit floor.
 

rogerthebodger

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I can't see any point in having an inspection hatch, as the tank is directly under the cockpit floor, so to get at the inspection hatch you'd need to either take the tank out or take an angle grinder to the cockpit floor.

If the tank can be fitted without taking an angle grinder to the cockpit floor it could be removed and an access hatch would allow cleaning of the tank anyway without totally removing the tank and trying to clean the inside through the small filler pipe.

I design to easier maintenance any time.
 

pvb

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If the tank can be fitted without taking an angle grinder to the cockpit floor it could be removed and an access hatch would allow cleaning of the tank anyway without totally removing the tank and trying to clean the inside through the small filler pipe.

I design to easier maintenance any time.

How often do you intend to clean a fuel tank? Unless the diesel bug strikes, they are fit and forget.
 

sarabande

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yesbut, yesbut.... The probabilities are low, but the consequences, both financial and time, in terms of gaining access to an otherwise closed tank, are tremendous.

Pay £20 now, or £100 in ten years time ? How's OP's cash flow and risk averseness ?
 

pvb

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yesbut, yesbut.... The probabilities are low, but the consequences, both financial and time, in terms of gaining access to an otherwise closed tank, are tremendous.

Pay £20 now, or £100 in ten years time ? How's OP's cash flow and risk averseness ?

But if you start off with a new tank, and dose the fuel with biocide, what realistically is the chance of having to clean the tank in the next 10 years, or 20 years?
 
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