Plugging Old Knotmeter Hull Holes

[casey1999]

I have two knotmeters on my baot that are no longer used. The knotmeter transmitters go through a hole in the bilge area of the boat (this allows the paddle wheel to go into the water). How can I plug these holes? For now the old knotmeter tranmitter is left in place, but I would feel more secure if it was a permanent plug like a fiberglass patch. As it is if the tranmitter gets knocked out- the boat would sink.

[mitiempo]

You grind a taper on the outside of the hole, about 8 to 1 ratio. Grind the inside as well, but not to the same extent. Mix epoxy, thicken it and fill the open area after taping the outside. Cut circles of biax roving, enough to build up the same thickness as the depth of the area to be filled, in several diameters the largest the size of the area you ground out. Wet them with epoxy and place them on the outside, starting with the largest circle and ending with the smallest. After it has set fair with thickened epoxy and bottom paint. On the inside a layer or 2 of biax in epoxy and you should be done. Fairing isn't usually a big issue in the bilge, just make sure there are no sharp edges.

[LandLocked66c]

Originally Posted by mitiempo

starting with the largest circle and ending with the smallest. After it has set fair with thickened epoxy and bottom paint. On the inside a layer or 2 of biax in epoxy and you should be done. Fairing isn't usually a big issue in the bilge, just make sure there are no sharp edges.

Don't you mean, start with the smallest and end with the largest?

[mitiempo]

No, start with the largest. This is the advice of most now as when sanding there is no chance of going through the large one, the one that adds the most strength.

[LandLocked66c]

Not computing? This is what i'm thinking...



Fiberglass Repair by Don Casey

[mitiempo]

Not the first time Casey was wrong.

The biggest circle is the one providing the most strength. When you sand it the biggest one, if outside, will be abraded or sanded through. By reversing the order that chance is eliminated.

Also I would use biaxial roving. 1708 has mat on one side and is fully epoxy compatible. Most mat is not compatible with epoxy. It will only take a few layers to build up enough thickness. With cloth and mat many more layers are required.

[LandLocked66c]

My world is now turned upside down!

[Beersmith]

Originally Posted by LandLocked66c

My world is now turned upside down!

me too

[LandLocked66c]

So what else have I been mislead on? This just isn't right!

[rayncyn51]

That "biggest first" concept fried my head, too, at first. But if you think about it, the big patch touches the most hull this way, and it has the most protection. It's really much stronger.