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no eye deer
27-07-2010, 07:37 PM
Which silicon?
I was going to use Selleys Marine, but it has the "vinegar":P

I am going to use a blob under the fuel/ battery tray at the transom, by the bungs.
So, I guess Sikaflex. But which one? Anything cheaper?

thanks fellas,
Mark

Alli boat of course......

bigjimg
27-07-2010, 08:01 PM
Make sure the mounting surface is rubbed clean with thinners or acetone,and the base of the pump which is plastic give a rub with 100 grit to key well and dust off.Don't go overboard with the amount as will stick like Sh@#$t to a blanket,as you may want to remove at some point.Silicone will give off that Vinagar smell only while it cures.Sikaflex polyurathane sealant/adhesive will be the best bet,11FC or similar will do the job.You could go the Marine one but the construction ones are just as good.Jim

ozscott
27-07-2010, 10:01 PM
Mate Silicon in particular is adversely effected by petrol So if you get fuel spill in the bilge that can get to the adhesive it will lift in time. I decided that it was also too hard to get the pumps to stick with just silicon or even blobs of sika cause of the relative lack of mounting area (and you dont want the crap to go up into where the water gets sucked up because it reduces how affective it is). I ended up cutting up one of the poly cutting boards (from the kitchen - or you can use a Polycraft....:)) and I just mounted pieces of that where I wanted it by rubbing back the surface with sand paper and then wiping down with prep chemical and then putting down a big layer of sika and gluing the kitchen cutting board onto that. Then I screw down the bilge pumps to the cutting board. I have never had any dramas since doing this, but plenty before.

Cheers

Angla
27-07-2010, 11:42 PM
I also fixed a poly board material down to screw the bilge pump to. Watch out for silicon around motor sensors. Neutral cure I believe is the go if that is your choice. I set mine into position with my fiberglass, 2 part patching stuff.

Cheers
Chris

therapy
28-07-2010, 12:38 AM
I used a bracket myself. Easy to fit through the inspection port for the bilge and no messy silicone's or sicca's. If you have easy access I would suggest buy a bracket and do it that way.

Cheers.....Terry.......

death_ship
28-07-2010, 06:27 AM
silicon wont stick to polypropylene

no eye deer
28-07-2010, 06:48 AM
Thanks fellas,

i like the idea of the cutting board. (The missus doesnt though).
I'll go with that.


Mark

no eye deer
28-07-2010, 08:02 PM
What do ya'll reckon about check valves (for the bilge hose)? "Rule" says No.
Any opinions?


Mark

cormorant
28-07-2010, 08:12 PM
They are more designed for belows style manual pumps where they work better with a prime and can draw over a long distance. On my cruiser the manual bilge pipes are long and can hold 6l of water . The stop valve works well on it but they do like anything affect flow rate. The pulse from bellows pump seems to keep em clear of debri.

no eye deer
29-07-2010, 06:56 AM
Thanks Cormorant,
thats what I thought. Didnt know that about manual bilge pumps.

Mark

Grand_Marlin
29-07-2010, 08:59 AM
If you use Johnson Pumps they have a check valve (Flap) built in - work really well.
Non return valves can be used ... but remember they are affecting the capacity of your pump.
I prefer the Whale brand non return valves with the "star" opening centre if I absolutely have to use one, but prefer to fit the Johnson Bilge Pumps as my first choice.

As far as mounting with Sika etc. as was stated earlier, any silicone is not resistant to fuel / oil which always seems to find its way into the bilge.
I always mount with screws whenever possible, but sometimes there is no choice but to stick them down.
I thoroughly clean and lightly sand the hull surface, more heavily sand the bilge pump base, and stick it with 2 part epoxy.
Very strong, resistant to fuel, and it allows you to mount the bilge pump as low as possible in the hull so it picks up maximum water.

Cheers

Pete

oldboot
29-07-2010, 09:55 AM
I know many will know this.... buy sicaflex is not silicon.....it is polyeurathane...chemicaly and practicaly a very different product.

I have come to the conclusion that there is almost no viable use for silicon sealer on a boat.

The acetic acid ( vinegar) if used on metal will cause a permanent corrosion problem,
Silicon has many thigs that will cause it to fail to stick or peel up.

Even the non acetic cure silicon has its problems...it does not perform as well at the acetic cure type and it can still help corrosion.

It is just horible nasty stuff.

Polyeurathane sealer, sica( various), bostic gold and a couple of others are a far better product for marine use

depending on the pump used have you thaught about using a plastic mounting bracket there is one that will take three of the round rule pumps.....you can then screw to a vertical surface (perhapss your cutting board), and then get the pick up all the way to the bottom of the bilge.

In a small power boat, where you have a very short lift and a short hose, why would you want a non return or check valve.....all a check valve will do is permanently hold water in the discharge hose where it can fester, and considerably reduce the flow of the pump.

keeping the discharge path as smooth and as short as practical will realy improve the output........just changing from corigated to smooth pipe will yeild a singnificant improvement in flow.

And with bilge pumps it is all about flow.....isn't it.

cheers