Through hull fittings for steel hull (again)

[rogerthebodger]

While we're on this subject, this is where the pump will be mounted (yes, the bilge is in the process of being re-painted):

View attachment 63852

Any good ideas for how to attach the pump to the inside of the hull? Welding some kind of brackets?

I mounted one of my pumps on an angle bracket bolted to a rib so the the bracket pump mounting was parallel to the hull plate but distant from it by the height of the ribs with the pump mounted to the bracket face that is parallel to the hull plating.

 

[Lomax]

I mounted one of my pumps on an angle bracket bolted to a rib so the the bracket pump mounting was parallel to the hull plate but distant from it by the height of the ribs with the pump mounted to the bracket face that is parallel to the hull plating.

That sounds like what I had in mind, but "bolted"? I'm very reluctant to drill into the ribs/stringers, perhaps I shouldn't be?

 

[[70521]]

I am fitting two Whale Gulper 320 pumps as bilge pumps on a steel hulled boat - what material is best to use for the (above the waterline) through hull fittings?

All the through hull fittings are plastic/nylon on my GRP boat, I can't think why anybody ever fits anything else.

 

[Lomax]

And speaking of drilling: will I be able to drill a 34mm hole (1" BSP clearance) in 6mm steel with just a Starrett TCT hole saw and a hand-held drill? Or do I need one of those magnetic drill bases? What cutting fluid should I use?

 

[rogerthebodger]

And speaking of drilling: will I be able to drill a 34mm hole (1" BSP clearance) in 6mm steel with just a Starrett TCT hole saw and a hand-held drill? Or do I need one of those magnetic drill bases? What cutting fluid should I use?

View attachment 63861

Don't use a TCT hole saw as any vibration (and there will be vibration when drilling by hand) will chip the TCT. I use normal bimetal hole saws and I have drilled for 1 1/2" bsp in 6 mm mild steel without a problem with a bit of oil for lubrication.

I have even used bi metal hole saws on 316 stainless steel in my lathe/milling machine.

https://www.google.co.za/search?q=b...AhXLC8AKHRmsC2wQsAQIcA&biw=1920&bih=901&dpr=1

 

[Solent sailer]

That sounds like what I had in mind, but "bolted"? I'm very reluctant to drill into the ribs/stringers, perhaps I shouldn't be?

why not glue a wooden backing board to the appropriate area? they seem to glue everything now and a 12" pad of 1" ply sikaflexed to the hull would be pretty permanent!

 

[Lomax]

why not glue a wooden backing board to the appropriate area? they seem to glue everything now and a 12" pad of 1" ply sikaflexed to the hull would be pretty permanent!

I had thought of this; glueing and then painting in waterproofed wood. Easy to do, and easy to attach things to, but I worry that you can't remove it cleanly if you change your mind. Not sure how durable it would be in wet areas. A welded bracket needs minimal contact surface and is easier to remove, but requires a welding machine and the skills to use it. Been looking at "portable" (flux core) MIGs but it's a bit of a jungle - any recommendations?

 

[Solent sailer]

I had thought of this; glueing and then painting in waterproofed wood. Easy to do, and easy to attach things to, but I worry that you can't remove it cleanly if you change your mind. Not sure how durable it would be in wet areas. A welded bracket needs minimal contact surface and is easier to remove, but requires a welding machine and the skills to use it. Been looking at "portable" (flux core) MIGs but it's a bit of a jungle - any recommendations?

Flux cored mig always looked like the worst of both worlds, low penetration of a small mig and still flux as with stick welding. If you want a mig why go flux cored? several company's now sell the bottles in decent sizes so rental on the gas isn't an issue, stick welding would be cheaper a better job and should be easy enough for what you are doing. Tig is very versatile and give you the option of welding SS fittings etc. if you are investing in new kit. The main problem I can see with welding is it will burn the paint of the outside, is that a problem?
You can always get the glued plywood off with a chisel a but at a time, then scrape the glue off again with the chisel - marine ply should last pretty much forever especially if painted or epoxied.
have a look at http://www.r-techwelding.co.uk/ I got some kit from them a few years ago and have been happy with it.

 

[Lomax]

Don't use a TCT hole saw as any vibration (and there will be vibration when drilling by hand) will chip the TCT. I use normal bimetal hole saws and I have drilled for 1 1/2" bsp in 6 mm mild steel without a problem with a bit of oil for lubrication.

Thanks, that's very good to know - not least since the TCT type tends to cost a lot more! I'll get 27mm and 34mm (3/4" and 1" BSP clearance respectively) bi-metal hole saws from Starrett instead then, unless there's a particular type/brand that's better?