Replace Blake's seacocks - what to do with bolt holes

[infaddict]

Hi, I am replacing some very old and corroded Blake's seacocks with Tru Design composite ones. The Blake's are secured with 4 bolts so when removed I need to fill these 4 holes. As they are below the waterline it's super important they are filled correctly. I have a solid fibreglass boat and hull.

My plan was to sand/rough up the insides of the holes using a Dremel tool, then put some masking tape over the outside of the holes. Then mix up some thickened epoxy, probably with some silica or chopped strand. And fill the holes.

Is this a suitable repair strategy for under the waterline? Any advice appreciated thanks.

 

[Stemar]

Provided the hull is reasonably thick, that should be fine. I'd be tempted to taper the holes a little using a taper drill, but I'm not sure how much that would add. If it's cored, I'd take out maybe 1cm of core around the hole and fill the whole lot.

 

[RunAgroundHard]

Download "FIBREGLASS BOAT REPAIR & MAINTENANCE". Section 4.0 will likely give you the advise you need to reinstate full strength.

Publications - Wessex Resins & Adhesives

 

[infaddict]

Download "FIBREGLASS BOAT REPAIR & MAINTENANCE". Section 4.0 will likely give you the advise you need to reinstate full strength.

Publications - Wessex Resins & Adhesives

Thanks. That suggests a full bevelled repair of any sized hole. Which would mean completing grinding the entire old thru hole and glassing over. Then recutting a new hole for seacocks. A huge amount of work (I have 7 to do) but if it's the best and only way, so be it.

 

[steve yates]

Would it not be a lot less work to replace them with other blakes? They are about the best seacock you can get.
And also on those lines, do they really need replacing? A lot of old boats have decrepit looking old siezed blakes seacocks, that are transformed just by removing them, cleaning them up with petrol and lapping the cones with blakes grinding paste. Much less work than filling the holes.

 

[vyv_cox]

My choice would be to retain the Blakes if at all possible but it would be interesting to know their age. Mine are 40 years old and in good condition. This was exactly when the first DZR ones were introduced, prior to which they were a grade of bronze, my guess LG2. Based on colour mine are DZR.

 

[Caer Urfa]

There's no quick fix to do it properly. the holes are probably about 10mm dia and you need to count sink each hole inside and out to say to 20mm dia
After cleaning and sanding the area cover the outside hole over first with something plastic and start covering inside with say a 12mm dia fibreglass cloth cutout/resin, then another say 16mm dia and build up say halve filled, then do the same outside, fill both sides until proud of the hull thickness , outside can be sanded flush to suit later

However as above I would service the old ones , my last ones were 30 year old and worked fine, I always used Blakes 'green; own grease

 

[RunAgroundHard]

Thanks. That suggests a full bevelled repair of any sized hole. Which would mean completing grinding the entire old thru hole and glassing over. Then recutting a new hole for seacocks. A huge amount of work (I have 7 to do) but if it's the best and only way, so be it.

I would look at the guide as just that, a guide, not a regulation that you follow. Then try and meet the intent that was both reasonable and secure. I did think much the same as you note and agree with your comments. On my own boat I recovered a 4 inch flue hole in the couch roof following the same guide, but filled a small 15mm shower draIN outlet (above the water line), just by tapering the inside and outside. I did fill as you suggest in your OP, but used glass cloth inside and outside to cap the plug of GRP.