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  1. #16

    Re: Bilge pump size for 4.3 mtr tinnie

    Bubs,go with the biggest you can get to fit as it is like insurance, you hope not to use it but when you have to you'll be glad you were covered.

    Chris, Stacer offer the full floor as an option, not the dealer.

  2. #17

    Re: Bilge pump size for 4.3 mtr tinnie

    Quote Originally Posted by tunaticer View Post
    Everything depends on the room to fit a bilge pump.
    My tub only has 115mm from the hull to the floor so I make do with a 500gph bilge pump.
    It has never really been a issue for me, takes about 5 minutes to drain the hull when the water comes above the floor.
    Rule have a low profile bilge pump these days - 900 gal/hr in both auto and manual ($130 Auto)

    Give a man a fish & he will eat for a day !
    Teach him how to fish
    & he will sit in a boat - & drink beer all day!

  3. #18

    Re: Bilge pump size for 4.3 mtr tinnie

    If space is an issue get a manually switched pump with a hose in each end that way you only need 25mm

  4. #19

    Re: Bilge pump size for 4.3 mtr tinnie

    Really depends what you want a bilge pump to do, for example if you just want to empty out the boat from a bit of rain or spray then a small one will do, however if you want to get rid of a heap of water after a wave has gone over the front or over the stern then get the biggest one that will fit.

    My thoughts on this are, that if you have taken a wave into the boat, that will add a huge amount of weight to the boat and that will also make it more likely that you will be prone to getting another wave very soon after as the boat is now heavier and the water will slosh around from side to side, usually to get a wave into the boat means that the seas are quite rough or a breaking wave or that you have done something stupid and with the extra weight you will want to get rid of it as quick as possible.

    Whilst 500 US Gallons an hour sound a lot it really isn't (1 US gallon = 4lt), it equates roughly to about 33.33lt/minute. A 1/2" garden hose would probably fill a a container with about 50lt in the same time. So if you cop a wave that adds 50US Gallons or (200lt and 200Kg weight) it would take about 6 minute to empty which is a very, very long time in a rough sea. As the hull lifts on one side because of wave action, that additional water and weight will go to the opposite side which will contribute to taking in more water over the sides now.

    My last couple of boats have been of a reasonable size

    1) 23ft with a self draining floor so bilge pumps weren't all that much of an issue, however I still put in a 3700US gallon pump in.
    2) A 26ft boat with normal floor, so I added 3 x 3700US gallon pumps.
    3) My current boat is an 18.5ft and fitted it with a single 3700US gallon pump but it has 2.2m3 of positive flotation built in so shouldn't sink even if filled up.

    While these sized pump are generally overkill for most situations, you will be wishing you had a big one if the worst happens, especially in a small boat. I directly wire mine to the battery with a automatic float and waterproof fuse, the big ones use about 15A so if the worst happens they will run quite a while before the AGM battery goes low. Bear in mind that if the battery is submerged there will be additional battery drain with the terminals submerged in salt water. At least I will be floating on the top instead of resting on the bottom of the sea. They are not that expensive, the big ones start at about $55 on E-Bay and about $15 for the auto float switch, which works out being a fairly cheap safety insurance and peace of mind. The thought of floating in the sea with a live jacket on, absolutely holds no appeal to me whatsoever! On a small sized boat, these large pumps may not be able to be fitted but at least go as large as you can, bigger the better.

    Just my 2 cents worth.

  5. #20

    Re: Bilge pump size for 4.3 mtr tinnie

    A point Edberg touched up was about the batteries, if they are awash with salt water they'll stop working and so will your bilge pump, salt water in the cells kill them very quickly also. So basically have your batteries as high up as possible and preferably not where they are exposed to salt spray. I have a deep cycle battery for my Leccy up front under cover as well as a starting battery at the stern, the bilge is wired via separate switches to both so if one dies the other should hopefully operate.

  6. #21

    Re: Bilge pump size for 4.3 mtr tinnie

    That's why I like AGM batteries, as they are almost fully sealed, so salt water will take a long time to get to enter the cells, they are as sealed as possible especially compared to normal type/sealed batteries. On my boat, the battery is in a separate compartment in the back and whilst that compartment isn't 100% fully water tight, it will take quite a while for any significant amount of water to work its way up to the terminal height to cause trouble. That said, by then hopefully the large bilge pump will have done it's job. I am thinking about putting in another 3700 Gallon pump in the front as well but have to do a bit of modification to fit a decent battery and the pump up there first.

    As the OP has a smaller boat his options are more limited but I would still advise him to get the biggest pump he can fit and there may be improvements that he might be able to make regarding to battery type or pump position/size.


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