Drilling holes in side of my aluminium boat advice

[FNQCairns]

A question for anyone with structural aluminium experience or knowledge.

I have 2 skin fittings to place in the side of the aluminium boat for bilge pump outlets the biggest will be 1 1/4 inch the other probably 3/4. The boat sides are 900 high and not pressed.

Is 30mm from the closest edge of the drilled hole to the back of the boat where the 3mm side sheet is welded to the transom 3mm (I think) sheet too close:-/ .

I would like to have the hole this close to the back because it will make the bilge pump hoses easy to route and out of the way but not if it will cause problems later.

If it were steel I would probably just do it but I don't quite get aluminium.

thanks and cheers fnq

[Oh Gee]

I'm no engineer but I can't see a problem.

[blaze]

Hi NQ
Have you seen them ultra light flat support/gusset plates they make for things like race cars etc, hi tensile ali but nearly all holes to make them lighter. Dont think you will have a problem. I would have drilled the holes and had your thoughts as an after thought and not a before thought. Always weld the buggers up later if needed (I know, dosnt look pretty)
cheers
blaze

[finga]

You'll be fine :)

[FNQCairns]

Thanks Fella's will do, with slightly shaky hands:)

cheers fnq

[krazyfisher]

the skin fittings will most likely make it stronger if anything

[hervey_bay]

Was your concern the actual drilling of the holes or the placement ?
If it was the drilling , just use a hole saw , not too fast and use WD40 or similar as a lubricant , even kero.
Dress the sharp edge with a small half round file afterwards and it'll be perfect.

[FNQCairns]

Krazyfisher that's a good thought it is plastic though but must add back some of the strength I took away.

Hervey thanks, no problem with the drilling apart from the fact it is in the side of the boat and to put a cheap crappy piece of plastic in:( damn aluminium.

cheers fnq

[hervey_bay]

Any loss of strength in that area is likely to be negligible , especially if there is a corner gusset above. Presumably you'll be using a submersible pump , these pumps ( as you probably already know ) have no non-return valve as standard , so just put your skin fitting up as high as you can and you'll be fine.