Boat Building Forum

Find advice on all aspects of building your own kayak, canoe or any lightweight boats

Re: Other: Sanding the bottom
By:StephenHJ
Date: 4/15/2011, 2:13 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.

Isn't this a similar effect to the dimples on a golf ball? They are supposed to make a golf ball fly farther by creating micro-vortexes of "dirty air" around the ball, allowing it slip through the air easier. Also kind of like how boats staying in another boats wake can go faster, or slip-streaming in cars/bikes.

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