Condensation Options

[Jumpus GooDarus]

Well read back Fed I said my breather line is around 5 meters long

How quick would a pin hole opening block up with such a small orifice ????????????????

Not to mention pressure buildup in the tank

Everything is done for a reason in the small boat breather lines aren't such are big run so I used smaller dia

ps] In the big boat it may me 25 mm tube but it's got a 3 mm wall thickness so opening is 19 mm

[Fed]

I didn't say to use a pinhole, all I said was that's all that was needed to relieve the pressure, 5M or 50M it makes no difference.
Larger sizes are used to stop any physical blockages but there is no way you need to go to 1".
Does this tube slope downhill from the transome to the tank, if so then what stops rainwater running down it?

[Jumpus GooDarus]

Well you better look up my boats manufacturer Fed & have a go @ them cause breathers came with the boat & are welded in

I've build quite a few tanks over the years & have to agree with what they've done makes perfect sense to me esp with tanks below a sealed floor.

Breather line rises around 80 cm's tucks under the gunnel where its tacked into position then welded into the transom.

Even my fuel lines out of the tank were around 15 mm dia with a 5 mm wall thickness B4 I replaced the tank with the 2 new stainless ones

[Fed]

Just because they make boats doesn't mean they know what they are doing.
Is the breather welded where it passed through the floor, perhaps they used a 1" tube to make it easier to weld with the heavier wall thickness. I didn't say 1" was wrong other than the explosive potential and it doesn't need to be so big to function properly, you'd have to agree with that. I'd hate to light a match at the transom outlet on a hot day. :o
The fuel lines could have been oversized for the same reason I guess.
The whole thing's a bit awkward thinking about built in tanks below a welded sealed floor, how are you supposed to inspect this stuff? Interest eh?

[Jumpus GooDarus]

Just because they make boats doesn't mean they know what they are doing.

I totally agree Fed seen some shonky work & there's always the case employee's leave a Co to start their own brand without having a clue other than how to slap a boat together but in my case I think they built my tub well except there were no drain off holes along the ribs which resulted in corrosion within the hull that's why I rebuilt the boat last year.

Original fuel tank was bolted in & with all such type boats with sealed floors an inspection panel gets sealed into the floor allowing access & yes breather & fuel filler tubes are welded through the floor this is done so no water spills into hull, short hoses are then used to conect these to the tanks.

you'd have to agree with that. I'd hate to light a match at the transom outlet on a hot day.

Just as much if not more chance of an explosion with a smaller orifice it's no more dangerous if fact alot safer than having breather inside the boat where fumes can get trapped back inside the boat @ least the way my setup is fumes disipate into the air

The fuel lines could have been oversized for the same reason I guess.

Wouldn't have done it any othe way fed remember my hull is 5 mm plate & if you were to say weld 8 mm tube to it best you could hope for would be a 1.6 mm wall thickness dosen't make for a good weld even though it's only stitched & there a good chane you'll blow a hole cause you need to pump up the amps to melt the alloy

[Fed]

Just as much if not more chance of an explosion with a smaller orifice it's no more dangerous

Do you make this stuff up as you go?

[Jumpus GooDarus]

Just replying to your suggestions thats all & use my noggin in the process

If you've got a small escape route for pressure then there a bigger pressure buildup inside the tank isn't there ???????

A larger opening relieves pressure from the tank @ a quicker rate

[Fed]

If you've got a small escape route for pressure then there a bigger pressure buildup inside the tank isn't there ???????

Not relevant when you consider the slow speed of the pressure build up.

Have you ever modified any of this system from new?
What size is the breather at the tank, 25mm? (And is it the same as the one in the old tank)
Was there ever a fitting on the transom that covered the breather outlet or something?

This has gone way past condensation although it may be part of the cure.
Are the original manufacturers still in business, I'd be interested to see what they say about this, don't want to see the good ship Jumpy go BOOM!

[Spudly]

Maybe FED put the water in th tank!!!

See, I think Ive figured it out!!!

Brather size isnt so relevant I dont think, Some fuel tanks are actullty fitted with one way valves that allow expansion but no suction, Ie i think i reffered to diffs in an early post (stop them sucking in water when they are rapidly coold when doing a river crossing) (this can place axle seals at risk of popping out of position so extended breathrs are a better option)

However moto X bikes also run a one way valve.

[Fed]

It's easy to imagine a hot diff sucking in some water when it cools quickly, they say trailer wheel bearings are prone to the same thing.
I believe it.

[Jumpus GooDarus]

Here's food for thought for you Fed !

Another advantage of having a large breather is ??

I refered to pressure buildup inside the tank well pressure can also build up when filling tank as well & nothing worse than those silly fuel pumps cutting out on you because the fuel has come up the filler line.

I get no such probs because my breathers get rid of pressure buildup in the tank very nicely & i know went tank is full when a bit of fuel comes out the breather, no spilt fuel enters my boat

[Fed]

Yep an extremely valid point especially with those rubber things they use on the pump necks now.
I just don't feel comfortable thinking about a 19mm vent pipe without a flame arrester fitted.

[Jumpus GooDarus]

Well when you finally get to see the Boat you'll see for yourself & eill agree it's a very good set up

Think it's a bit hard trying to explain things I have this saying that I think is quite good

Show Me, Dont Tell Me


Not everybody thinks the same or can picture things the way they are explained

Cant recall but think on my old big moored boat the breathers were quite large on it as well bear in mind I had 2 off 1000 litre tanks on it & the fuel was diesel no petrol

[Fed]

Go and Google "flame arrester" mate.
Unless there's something you haven't told me then you're sitting on a bomb.