products used to protect hull

I got an 83 H16 a year ago and have worked through some of the more obvious rebuild/maintenance projects to get it on the water. I still haven't done anything to protect the hulls from UV & salt water and keep them fast. What do you use to on your hulls? Someone in a post recently said he wetsanded with 800 grit sandcloth and then coated it with ZEP wet look floor finish. His hulls looked great, and the price seemed affordable, but I wondered if it did anything for UV protection, how it worked in salt water, and if it might slightly cut down on boat speed. I thought about buying some McLube HullKote until I saw the price and something on their webpage that said that 2-3 coats would work for 20-30 days.

A lot of people will take an oxidized gel coat and sand it and depending on how bad go thru the various grits 600, 800, 1000 and then rubbing compound to get the gel coat color back to something close to the original. Whether you want to you use zep or a quality polish is up to you and I don't believe any of them have a UV rating so if you are looking for UV protection then cover the boat.

Now surface prep for speed is a whole new conversation. 25 years ago when I attended my first hobie mid winters in San Felipe I saw "A" fleet 16 sailors sanding their hulls horizontally under the water line area with 400-600 grit to minimize the water resistance much like many years later the US Olympic swim team using the swim suits that where textured to be like fish scales because the flow tanks showed that they went thru the water with less resistance.

Personally, I look at trying to maintain and keep my boat looking as good as I can for as long as I have it so I buff it out with a fine rubbing compound every other year and polish it with a quality marine polish twice a year and try and keep it covered or garaged as much as possible. As far as sanding it down with 400 grit before every race I prefer to keep my hulls in the best condition that I can and forgo those extra 10-20 ft I could have gained in one race...that is if it works.

_________________
2001 H18 w/SX wings & spinnaker #16740 (purchased new)
1989 H18 w/SX wings #14565 (purchased new, sold 2000)
Would buy another if Hobie would build it.

The best way to protect it from the UV is to keep it covered or out of the sun. The next best thing would be to mechanically buff, polish, seal and wax the hulls. The idea is that UV radiation hastens the breakdown of the gelcoat and the polyester resin that bonds the fiberglass together. This is separate from oxidation of the gelcoat, which is caused by the resin in the gelcoat chemically changing/breaking down from exposure to oxygen. Similar to rusting steel, oxidation is only on the surface.

The solution for the two problems is the same: buff and polish the boat. You may need to sand the hulls if they are severely oxidized. Sanding would probably start at ~800 or 1000 grit, stepping up to 1200, 1500, 1800, 2000, and then continuing on to buffing the hulls with a rubbing compound, then polishing the hulls with a polishing compound. This is mechanically removing the oxidation from the hull. The next step in protecting from oxidation would be to seal and/or wax the hulls with a good, high quality marine sealant and/or wax. If you can create a barrier to keep out the oxygen, your hulls will not oxidize until the barrier breaks down - so be sure to seal or wax annually at least. Now, how does this protect from UV? In theory, a more reflective hull will reflect more of the UV radiation away from the hull and therefore protect the resin in the gelcoat and fiberglass that much better.

As far as resistance is concerned, there is a point called "hydraulically smooth," which is the point that the surface profile does not create any added resistance moving through the water than would a perfectly smooth plate, due to the viscosity of the water and something called a "boundary layer." The surprising thing is that it's only about 600 - 800 grit or so. You can sand, buff and polish all you want, but as far as the water is concerned, it doesn't make much difference. You do want to keep the hulls clean, however. Wax actually creates more resistance, however, so most racers just keep the boat clean and covered.

_________________
Mike

'79 H18 standard 'Rocketman II' sail #14921 RIP
'78 H18 (unnamed) sail #14921
'08 H16 sail #114312
'97 H21SC sail #238