people are worried about what happens when a vertical drop dagger board
hits the bottom at speed. Surely it will get damaged?!?
experience is different - there is little damage on even fast boats and
the dagger board is much more efficient because of the smaller slot.
with Kai Mei on the dagger board being better than a pivoting
board. It does offer a lot less drag and is much easier to
fabricate and less prone to leaks and jamming. It also weakens
the hull less.
My Sailing Canoe has a dagger board and is about
the same weight as our PD Racers. But when it hits a rock or
sandbar it can be going 3 or 4 times faster than a PD Racer will ever
get to. This is not uncommon as I sail it on the lower reaches of
the Murray River which has more than a few shallow spots and limestone
outcrops. I also have a tendancy to go exploring which does put
protuberances at a higher than normal risk.
The energy involved
varies with the square of the speed - so the energy trying to break
things on the canoe will be 4 squared = 16 times greater than the
puddle duck will ever see.
Over 10 years of use I have had to
repair the centreboard two times - simply planing the trailing edge off
the board and gluing a new one on and planing down to the original
The case has never been damaged (always ensure it has
good bonding area to the bottom of the boat by having a transverse
frame glued to the back of the centreboard case.
The centreboard damage in both cases didn't affect the day's sailing either.
far as the daggerboards on the PDs goes - I took one of our two up the
Mooloola River and did prang with a mudbar/sandbar several times as I
navigated the unknown stretch - the boat stops with no drama and no
damage. Three times I hit a rock shelf (well I wasn't aware it
went right across the river so I hit it in three different places!)and
it resulted in a small ding in the centreboard leading tip (which
no-one else would be able to notice) and a small ding in the trailing
edge where the board exits the hull.
So I wouldn't worry about getting tooooooo technical with protecting damage from hitting things.
of the racing boats in Australia have dagger boards. Some just
use a piece of garden hose threaded down the back of the dagger
case and held with a single boatnail at top and bottom. The nail
is only put through the back face of the hose - not through both front
Tho' most people don't bother at all.
Swinging or dagger - it's up to you - no real practical difficulties either way.