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Re: Other: Sanding the bottom
By:Bill Hamm
Date: 4/15/2011, 6:14 am
In Response To: Other: Sanding the bottom (Malcolm Schweizer)

: Hello all,

: I guess this is what happens when you're too tired to sleep, but I
: was thinking about bottom paint after responding to Bill on
: using graphite in the bottom coat. It got me to thinking about
: what I have read and practiced in both sailboat racing and in
: surfing- sanding the bottom to 400 grit and leaving it at that
: as opposed to the nice shiny finish. What it does is causes
: water to adhere to the hull and creates kind of a barrier layer.
: The water molecules that "stick" to the sanded finish
: actually ride along with the kayak, so your hull is now riding
: on little ball-bearings of water molecules which reduce the
: friction. Is this making sense? I didn't think so.

: Well, it's been hotly debated on many forums. Think of it this way-
: take a nice shiny smooth hull and wet it down. Now run your hand
: over it. Your hand will get friction and sometimes even squeak
: as you slide it over the hull. squeeeeeeeeeek Now sand it to 400
: grit, wet it, then do it again. Your hand will smoothly glide
: over the hull.

: I just thought I'd throw it out here for discussion. It works! It's
: no big deal for recreational kayaking, and I don't want to
: create a great divide- sanders and non-sanders- but I would like
: to hear thoughts and comments.

: Somewhere out there is a youtube video that shows this effect but I
: can't remember what it was titled.

: BTW, I'm a sander, but for a pretty boat that I want to show off
: every inch of and don't really care how fast it goes I'm a
: non-sander. Call me a hypocrite.

It does work, though I've always wet sanded with 320 to get the effect. I wonder about it's use on a kayak/canoe though, what it does is make a thicker boundry layer of water "stuck" to the hull, I wonder if the added water "stuck" to the hull effectively increases the weight of the boat, just have no idea how much it would add. Been done for years on racing sailboats, part of the effect is the mental effect on your competitors, if they think it works on your boat, it does. Always helps to do a bit of final sanding right in front of everyone just before you launch ;)

Bill H.

Messages In This Thread

Other: Sanding the bottom
Malcolm Schweizer -- 4/14/2011, 10:59 pm
Re: Other: Sanding the bottom
StephenHJ -- 4/15/2011, 2:13 am
Re: Other: Sanding the bottom
Malcolm Schweizer -- 4/15/2011, 5:04 am
Re: Other: Sanding the bottom
Bill Hamm -- 4/15/2011, 6:14 am
Re: Other: Sanding the bottom
Malcolm Schweizer -- 4/15/2011, 7:24 am
Re: Other: Sanding the bottom
Bill Hamm -- 4/15/2011, 7:37 am
Re: Other: Sanding the bottom
Mike Savage -- 4/15/2011, 12:59 pm
Re: Other: Sanding the bottom
Dave Houser -- 4/15/2011, 3:13 pm
Re: Other: Sanding the bottom
Bill Hamm -- 4/17/2011, 1:16 am
Re: Other: Sanding the bottom
ancient kayaker -- 4/17/2011, 9:28 pm
Re: Other: Sanding the bottom
Robert N Pruden -- 4/18/2011, 9:01 pm