BWM Deep Sea 21

[Fizzwizz]

I recently bought a BWM Deep Sea 21, it's yellow with a Mariner 90HP 2 stroke outboard.

I bought this boat with the intention of restoring her to her former glory. For the money I think I got a great little boat.

Presently she has a plastic 20L portable fuel tank, but I notice she has under deck fuel tanks from the filler, vent, and disconnected fuel filter still bolted to the transom.

I assume that the tanks were made redundant due to leaks, I'd like to replace them. I'm sure this will involve cutting into the fiberglass deck to get access to them. Does anyone know where exactly they are located, how many there are, and where best to cut into the deck?

Many thanks

[Daniel]

Always wanted a DS 21!

I wouldn't assume they (probably "it" - unlikely to be more than one tank on that boat with 1 filler and 1 hose coming out...) are split.

See if there is anything in them first? Water would be a bad sign. Old stale petrol a good sign.

Then fill them up & test for leaks... It'll creak into the void between deck & hull and appear at the rear bung if there is... Not sure if I'd use fuel, water, or perhaps even red derv coz it won't contaminate the tank too much and it's cheap.

If your lucky and no leaks then it's just a case of flush through to try and clean out isn't it?

[Fizzwizz]

Originally Posted by Daniel

If your lucky and no leaks then it's just a case of flush through to try and clean out isn't it?

Hi Daniel. Thanks for the advice. You never know your luck, however I'm not hopeful (always the pessimist). I can't see why someone would abandon the internal tanks unless they were leaking. An integrity test with coloured water (DERV is 85p per litre) or air isn't going to be easy as I cannot find the fuel take off, which has probably been cut away. Any ideas?

Assuming these tanks are no good (as I suspect), does anyone have any experience or advice of how to get at them?

Thanks again

[Daniel]

My worry with water would be how do you ever get it all out? The pickup will be 1/2" at least of the bottom of the tank.

On my DS 18 the top of the tank protruded through under console, but assume you've looked.

If full access is what you want to do, you'll just have to start at the filler neck, fuel gauge or anything that's obviously part of the tank and spread out from there with what ever tool takes your fancy for cutting up the deck...

Rebuilding the deck will be a significant task in time, not an insignificant cost & certainly some skills needed.

[willk]

Originally Posted by Fizzwizz

I assume that the tanks were made redundant due to leaks, I'd like to replace them.

Nice buy and welcome to RIBnet.

If the price of a few gallons of DERV is putting you off doing the right thing, then you're in for a major shock when the tank replacement starts...

[Fizzwizz]

Originally Posted by Daniel

On my DS 18 the top of the tank protruded through under console, but assume you've looked.

I've been in there a fair bit pulling out old cables and replacing them with new. There's no tank protruding, though I haven't looked specifically. Its amazing how the eye doesn't see what it's not looking for. I was hoping that the tanks were going to be more aft, which is more accessible. It looks like the whole helm is going to have to come off.

I agree with the water in the tank problem, however, if the fuel take off is at the bottom of the tank it will be full of water anyway. The self bailing ball valve did a great job of partially sinking her with 6 inches of water above the deck. This was the first job, now done successfully.

I'm usually better at putting things back together than getting them apart. If I can get access without too much butchery, I have enough fiberglassing skills to repair the deck properly. The key is to minimise the number of test holes, and to remove the deck in one fuel tank sized piece. In order to do this I need to know the exact tank size and location. If I can get the tank out I'll have a new one made.

The cost is always a concern, and to be honest it would be more economical to sell her now (now in seaworthy condition) and upgrade to something newer (coincidentally I've been looking at Ribtecs). This is my first RIB (not including the tender to my sailing yacht). I took her for sea trial yesterday, and must say the bug really bit. We decided that it was worth buying something newer, but I wanted to make sure there were no more bodged jobs aboard her before I sold her to someone who may take his children to sea. She was full of bodge jobs when i bought her. All now removed and made safe. There's just the fuel tank (which is safe as it is, but the range is prohibitive), and a new tachometer and switch panel to fit (on order). I'm wondering if the tank is a job too far?

Many thanks again

[Fizzwizz]

Originally Posted by willk

Nice buy and welcome to RIBnet.

If the price of a few gallons of DERV is putting you off doing the right thing, then you're in for a major shock when the tank replacement starts...

Ha, true indeed. But if the tank is 200L and I can't guarantee all vents and outlets are plugged that's £200 and a big clean up that tells me nothing. Air is much cheaper! I think I need to find the missing fuel outlet. I can plug this and the vent and then pressure test down the filler hose.

Thanks

[willk]

You have some interesting decisions to make!

Personally I'd look at the BWM with a cold eye and decide how long you REALLY want to keep her (ignoring the tank issue). What sort of condition are the tubes in? If they are worn and you don't want her long term, then I'd tidy and sell on in the spring. If they're OK and you might keep her a few seasons, then the tank becomes more interesting. I'd test it before making any decisions. To do that, you'll have to find where it is and how it's set up. I DON'T know the layout of BWM tanks/consoles, but my old boat was a similar size and the filler point/pipe was in the console. That fairly much suggests one end of the tank just underneath, running aft. The breather will certainly be beside it. My fuel pickup was also below the console base, the fuel line rose into the console (passed through the fuel meters) and ran aft on the deck via the cable ducts. You're right about not seeing what you're not looking for. I'd take a torch and a small mirror and go looking again - unless the previous owner glassed up the spaces, there must be some sign! There will probably be a plate screwed to your deck somewhere - this will be above the fuel gauge sender and if you lift it, you MAY get a peek at the top surface of the tank with the mirror...

There are lots of reasons why the tank might not be in use. It may have given someone trouble with dirt and water - maybe too lazy to clean. It might have been used as a local boat and plastic tanks may have been handy for refuel/visual reassurance - someone who didn't use much fuel. Or it might be ruptured.

[willk]

Originally Posted by Fizzwizz

Ha, true indeed. But if the tank is 200L and I can't guarantee all vents and outlets are plugged that's £200 and a big clean up that tells me nothing. Air is much cheaper! I think I need to find the missing fuel outlet. I can plug this and the vent and then pressure test down the filler hose.

Thanks

Our posts crossed there

You won't have a 200L tank, more likely 140L ish. I take the point though. You need to find ALL the pipework first in ANY case. If you can find the sender cover, you could lift the sender and see INSIDE the tank. That would show you where the lift pipe is. You'll need special gunk to reseal the sender though (don't remember the name). Who knows, it might be half full of stale fuel - oh joy. Or seawater

Before you do anything - I'd get a price for a new 150L tank, with fuel sender and add in a cost for deck and glassing and recoating. It might help make up your mind....

[Fizzwizz]

Originally Posted by willk

Personally I'd look at the BWM with a cold eye and decide how long you REALLY want to keep her (ignoring the tank issue).

I think I've already decided not to keep her. Not because she isn't any good, she still has years of fun in her yet. The tubes are rubbed in places but now they are cleaned up don't look too bad. They hold air and don't seem too shabby. I've already spent a king's ransom on hypalon and 2 pack glue to cover the area where shore lines have rubbed and damaged the outer layer of hypalon. I was stunned to see how well she came up with fairy power spray (a golden Ribnet tip I found). The 90hp 2 stroke starts and runs well (though I had 2 spontaneous engine stops feeling very fuel starvation esque ... I was told this was typical for a 2 stroke ... is it?). Both times the engine restarted after 10 - 20 seconds of waiting and bulb pumping.

I want to sell her as I want to upgrade. I've fancied a RIB for years, but have been reluctant to spend a significant amount of money on a whim. Owning this BWM has been great fun, and I realise I have the bug so I'd like to invest in something newer. This being said, I'd like to make sure she's right for the next owner. The previous owner never used her and she was just dried stored. Every previous repair had been a bodge job. I would never have allowed anyone to take her to sea in the state she was in. The problem with cheap RIBs is they are often bought by people who can't afford to repair them. I'd like to think the next owner can get some fun out of her without unnecessary repair bills. I may be tempted to leave the tank, but the thought of it is tormenting the OCD in me :-)

Thanks again

[Poly]

Whilst I understand the suggestion to use Red Derv, I think it is probably flawed. you only need a few litres to see if there is a split near the bottom but you probably want to fill it to check the integrity near the top too. If the tank is OK what are you going to do with 100+ L of fuel thats been in a mangey old boat tank possibly full of rust and crap? If its not OK you've now got a load of crap fuel pouring or weeping all over the place. Throw a pint of milk of the floor and see the mess it makes - now imagine that with 200 pints of smelly, fuel that you can't just hose away and can't put in your car...

You should be able to test a tank just with air and see if it holds air.

I don't think water is a stupid suggestion though - you will be able to drain most of it - and almost all the rest you should be able to suck out with one of those pumps you get for removing oil from the sump via the dipstick. I'd definitely make sure there was a good water separator in the fuel line though for the final drips - and if you have a super sensitive injected 2 stroke (e.g. Optimax) then think carefully as they really don't seem to like water.

[willk]

Originally Posted by Fizzwizz

The problem with cheap RIBs is they are often bought by people who can't afford to repair them. I'd like to think the next owner can get some fun out of her without unnecessary repair bills. I may be tempted to leave the tank, but the thought of it is tormenting the OCD in me :-)

Again, if the price of hypalon and glue has put you off, the cost of a SS-tank and sender will blow your mind - time to sell me thinks.

The engine shouldn't be cutting out. It's certainly not typical of 2 strokes, unless possibly when operating slowly for long periods. If the fuel bulb was soft when you pumped it, then you have a fuel supply issue. Check for air leaks or restrictions.

[Fizzwizz]

Originally Posted by willk

Again, if the price of hypalon and glue has put you off, the cost of a SS-tank and sender will blow your mind - time to sell me thinks.

I think you misunderstand me, I'm not put off by the price. I'm no stranger to boat maintenance costs. I own a 48ft sailing yacht too which does blow my mind when it comes to maintenance costs. I'm happy to pay what I need to pay to get the job done right. If I intended to keep her I would invest in new tanks, tubes, and engine. I've already had a quote for tubes, but it doesn't make good financial sense to go this route, when it would cost more than a more updated boat. Maybe I should leave the tank, but it does seem a shame not to put her back to her original spec

Originally Posted by willk

The engine shouldn't be cutting out. It's certainly not typical of 2 strokes, unless possibly when operating slowly for long periods. If the fuel bulb was soft when you pumped it, then you have a fuel supply issue. Check for air leaks or restrictions.

Yes the bulb was soft each time. Something else to look at! :-)

Thanks again

[Dhf]

Does your console look like the one pictured, if so then your 120ltr tank will be raised inside the lower internal dimensions of consul about 2inch above deck level, I think "they" originally designed the consul around the tank tbh, I relocated my filter from transom to where pictured now.
I used one of those clear bottle suction pumps a few months back, just to check lower tank fuel condition, all good, and they work really well, infact with the bow raised it would be easy to completly empty the tank.
As for cutting out? I would sooner cut a section of deck out behind the consul, lets be honest there's loads of deck space to choose new location, dare I say, You could sit a fully loaded sr4 on deck and carry on regardless. not that you'd want to of course.

[Rokraider]

I have photo's of what is under the deck of a DS21. I had a jet project one on the go for a while and had the tank out. PM me with your e mail and I will send you some pics. I was rather alarmed to find that the tank sat on 3 wooden planks that were nailed with mild steel nails through the main bearers of which most of the nails had completely rusted away and broken, causing the tank to jam twisted in the bottom of the vee. Mine was definitely a Friday build.

[willk]

Originally Posted by Rokraider

PM me with your e mail and I will send you some pics.

Please Sir, may we have some pics too?

[Fizzwizz]

Thanks for that. I've been outside for a look. Beneath the front console is just the deck, no lumps, no sender inspection plate. I've had a look around the deck and in the rear seat compartments. Nothing but deck. The filler and breather go down together at the front of the console through a hole in the deck in the front console. I'm guessing it must be there somewhere but exactly where is a mystery.

Many thanks

[Fizzwizz]

Originally Posted by Rokraider

I have photo's of what is under the deck of a DS21. I had a jet project one on the go for a while and had the tank out. PM me with your e mail and I will send you some pics. I was rather alarmed to find that the tank sat on 3 wooden planks that were nailed with mild steel nails through the main bearers of which most of the nails had completely rusted away and broken, causing the tank to jam twisted in the bottom of the vee. Mine was definitely a Friday build.

Many thanks, I've sent the PM with my email. I look forward to seeing these pics.

[Fizzwizz]

I haven't received the pics yet, but in the cold light of day I can see the top of the tank where the filler goes through the deck. I cannot find any sender plate or fuel outlet though, which is a shame as I was hopeful it might have still been serviceable. Does the outlet usually rise to deck level near the tank, or is it likely to run under the deck to the stern?

I think I've sorted the engine stopping. It seems that 20 litres of fuel doesn't last long and when low it must be gulping air when sloshing around. Tilting the fuel tank back towards the pickup seemed to solve the problem. I definitely need to sort the internal tanks. I've priced up a new SS tanks with sender, which didn't seem too expensive, but I am also considering placing a plastic one under the front console seat. This would be a less disruptive solution than cutting up the deck, and would be easier for future maintenance.