Do I need to strip my bottom?

[Jim Cate]

Another tool is to affix a square, rectangular, or octagonal piece of plywood or plexiglass to a sander or grinder's pad. And then attach sheets of sandpaper to that. It prevents gouging, while allowing the removal of larger quantities of material with a fair degree of precision.

Unciv, I'm having a hard time visualizing this tool. Could you elaborate a bit more, please? That is, how does putting the abrasive on a rigid bit of ply keep it from gouging, where the softer, round pad does not?

I'm always interested in means of improving sanding technique!

Jim

[ramblinrod]

Originally Posted by Jim Cate

Unciv, I'm having a hard time visualizing this tool. Could you elaborate a bit more, please? That is, how does putting the abrasive on a rigid bit of ply keep it from gouging, where the softer, round pad does not?

I'm always interested in means of improving sanding technique!

Jim

He could be referring to a large diameter flat pad vs a 5" diameter drill driven rubber disc with centre held curled abrasive. (The latter will really gouge the surface.)

Any form of flat pad with hook and loop or adhesive attachment with 36 grit abrasive will work fairly well, except for any amount hardened cement-like above the waterline. (Those who apply anti-fouling well above the waterline ought be shot.)

[UNCIVILIZED]

Originally Posted by Jim Cate

Unciv, I'm having a hard time visualizing this tool. Could you elaborate a bit more, please? That is, how does putting the abrasive on a rigid bit of ply keep it from gouging, where the softer, round pad does not?

I'm always interested in means of improving sanding technique!

Jim

The idea seems counterintuitve to me too, & did for quite a long time. But if you consider a sander or grinder with a soft pad, & an agressive grit of sandpaper. If you leave the sander/grinder in one spot for long, due to the pad's softness, you can dig in an "edge" & cause a gouge. As the pad conforms to the convex curve of the hull, or even over-conforms. But if the sanding "pad" is flat, or rather, flat but mated to a soft pad, the edges of it can't/won't reach the surface of the hull while sanding.

Such a "pad" works similarly, "only different" on concave surfaces. The linked article describes it better than I can. Although in the end, naught beats 2 or 3 man longboards operated by some well schooled deck apes with tireless shoulder muscles.
http://epoxyworks.com/index.php/sand...-of-the-trade/

There are some other articles on sanding at the WEST System website if you use the search function there. Try typing in "sanding pad". And IIRC, the square pad (stop sign) trick is in their book The Gougeon Brothers On Boat Construction as well. And even if it's not, the book is one that anyone who works on boats should have (particularly newbies), especially as it's free at their website. Along with all of their product use guides, & project tips.
http://www.westsystem.com/the-gougeo...-construction/
http://www.westsystem.com/instruction-2/

[skipgundlach]

Originally Posted by UNCIVILIZED

clip...

Although in the end, naught beats 2 or 3 man longboards operated by some well schooled deck apes with tireless shoulder muscles.

clip...

We tried to make up a larger longboard, but in the end, the admiral wielded a 24" and I a 36" high-density foam longboard. We must have attempted something too large, because two very big guys couldn't move it. We did the diagonal sweeps described in the article about the expanded grinder base...

But all of that was after rough fairing with a grinder (albeit without base extenders).

The last step, however, is a trick snitched from metal workers.

Get some Dykem and dilute per batch 3/1 with acetone. Wipe it over the area you are fairing. Then long board it. Any areas not uniformly fainter - i.e. no color left or lots of color - are not yet fair. Lighter is too high, and darker is too low. Assuming you have enough material on it, always take down the lighter area first rather than build more.

You can see examples of longboarding and Dykem in the 3rd gallery, second subgallery of my bottom job link above (or here it is for only that portion) Pictures: Flying Pig Refit 2011-2012/Bottom Job/3 - Final Fairing and Longboarding

Aaannnddd...

I was in my supplier (Fiberglass Depot, in Ft. Pierce, a block down from Marine Liquidators) Fiberglass Supply Depot | Matt - Biaxal - Cloth - Epoxy - Polyester - Gelcoat - Table Top - Bar Top yesterday for more XL latex gloves.

They have an improved version of the AdTech fairing compound we used that they make under their Fasco label (also resins and many other neat stuff for us hacks), and what ALSO attracted me is that it's available in small quantities as well. Here's a link:
https://fiberglasssupplydepot.com/FA...-COMPOUND.html

As I have finished with the bottom, but might have a use for very small dings, that is very useful to me. Better yet, initial fairing can be done with a wet sponge, and sanding (as was the case in AdTech) is easy in about 4 hours, but like concrete after a full day. Our modus was to put it on very early in the morning, and do the rough sanding by the afternoon...

Danny has done everything there is to do to fiberglass in the more than 20 years he ran a repair shop in southern FL before going into manufacturing. Give him a call...

L8R

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