Sandblasting Aluminum hull and new plastic thru-hulls

[tronic72]

Originally Posted by George DuBose

I wouldn't use gate valves on a boat. I know bronze, copper and stainless steel make problems for aluminum hulls, but I see S/S stanchions isolated in their holders, so why can't a bronze seacock be electrically isolated from an aluminum hull?

He's using glass reinforced plastic, also called Marelon by Forspar. (Trudesign are all non-metal fittings). I'm doing the same on mine which negates the need for any electrical isolation.

[mitiempo]

Originally Posted by George DuBose

I wouldn't use gate valves on a boat. I know bronze, copper and stainless steel make problems for aluminum hulls, but I see S/S stanchions isolated in their holders, so why can't a bronze seacock be electrically isolated from an aluminum hull?

It can be electrically isolated easily - until the boat is in the water and then it isn't.

[xslim]

Let me put this thread back to question, as I did not fully got the answer.

Types of thru-hulls - Trudesign - glass reinforced nylon.
I already made a decision on them and I do not plan to change my mind on this topic.

Now because I plan to change all underwater painting (as it is 30 years old and in some places not holding any more) I need to decide at what stage I should put the new thruholes:

- before I send the hull for blasting (to be confirmed sand or soda or whatever)
- or after it comes back epoxied and primed

When I will send the hull to the paint yard to do the blasting, I will not have access to it till they blast it and then primed and epoxied it.

[soerencarlsen]

Then I would say! after it comes back epoxied and primed then go for installing your fittings according to manufatures recomendation !

[xslim]

Thank you all for suggestions!

We can close the thread now.