[mitiempo]

I agree with Mainesail. The higher the bronze fittings are the less force it requires to damage something.

If you use fiberglass mat beware that most mat is not compatible with epoxy. The binders that hold it together dissolve in the styrene in polyester. There is no styrene in epoxy. Only use mat if it is specifically stated "to be used with epoxy".

 

[mitiempo]

Groco has backing blocks similar to Mainesail's no through bolt method. They don't state what material they are, I guess fiberglass.

From Groco's catalog:

 

[mitiempo]

A slight deviation of the thread please. Does any build an enclosure around seacocks? The top of the enclosure would be above the water line so if something should fail the water is contained in the enclosure ?

Commonly done on metal boats and called a seachest.



I've never seen one on a fiberglass boat although this pic may be on a fiberglass boat.

 

[mitiempo]

On very bottom of the picture is picture of bronze thru-hull with straight thread.
Usually nut of some sort tightens(this is fancy one) it from the inside. This is all covered with lot of some kind glue to make permanent seal. Then comes ball valve with tapered pipe thread on both side. Question is how this can work straight thread and pipe thread?

It cannot work well. That is the reason for the flange adaptor shown in the picture. The other proper installation would be a true seacock which has straight threads where it mates with the through hull.