Planing

[Rick McDuffie]

Man, I had my first experience with planing yesterday. I've sailed for years, but usually in fairly calm winds- no more than 10 knots.

We were out in 14-15 mph winds, sailing along normally, when all of a sudden the boat just took off. I looked back and the water was rolling up in our wake like we were in a power boat. It was crazy.

I had heard this was cool, but wasn't prepared for how fast the boat would be.

I was also very impressed with how the DSII handled in those winds... very forgiving, but lively enough to be exhilirating.

Can't wait to do it again!

[gary l. britton]

Rick:

Congrats on planing your DS II. I also have been sailing for several years and have only experienced planing twice. Neither time was with my DS I. Admittedly, I am not a very good sailor, but I have fun. My only experience was with my old Sidewinder. It was a 1974 model and a fun boat to sail. I too experienced the sudden burst of speed and indeed it was a thrill. I wish I knew what I had done to make the boat plane. Any help from other DaySailer owners would be greatly appreciated.

Take care and have fun with you DaySailer.

Fair Winds

Gary
Dancing Girls II
1966 DS I #3235

[Rick McDuffie]

Thanks, Gary.

We had the wind on the port beam when we got up and planed. I felt the boat shudder a little, then we took off. My understanding is that planing is most likely to occur on a reach.

Is there anything that can be done to "coax" the boat to plane when all the conditions are right?

[Roger]

When you think your boat is almost ready to plane, ensure that you are sitting well forward, that your boat is as flat as possible, and absolutely 'square' to the wind, ie 90 degrees. Going forward gets the transom out of the water and reduces drag, and being flat, presents the best planing surface to the water. Square to the wind, maximizes the power. Look for the gusts, that will get you onto a plane and plan for them.

Planing is likely to occur at 1.5 times the factor of the speed/length ratio defined as the speed divided by the square root of the length. (The hull speed of a vessel is 1.34 x the square root of its waterline length in feet. Speed is expressed in knots).

You can predict when a boat is approaching its maximum hull speed by watching the numerous short waves that the hull drags along with it. As the boat speeds up, the number of waves decrease and the lengths of the waves increase, until there is only one wave, with one crest at the bow and the other just behind the transom. This is hull speed. Surpassing hull speed, the boat will climb the bow wave, and leave the stern wave behind.

In english: for our daysailers, which have a 16 foot waterline, hull speed is 5.36 knots. (1.34 x sqrt 16)

Planing starts therefore at (5.36 x 1.5)=8.04 knots, but may increase to a factor of 2 or 3 (10 to 16 knots).

Since I got rid of my 50 pound motor and 30 pound tank at the back of my boat, I have noted that my top speed (according to my GPS) has climbed from about 5 or 6 knots to 13 knots on one occasion and for a brief moment. I did not even realize that I had it up on a plane until I checked the gps' max speed after the sail. Now I plan, anticipate, and work for it.

[shawn]

I have been sailing a DSII for a few years and regularly get planing in anything above 12 kts. Both with and without a spinnaker but once blowin' 15 kts it doesn't seem to make a difference. For planing a broad reach (wind coming over the quarter) seems best and I actually move myself and crew back to get the bow out of the water and expose the flat planing surfaces in the stern( definitely have to keep the boat flat). Don't forget to lift the centerboard! For pointing I do exactly the opposite to get the bow in the water and help with pointing, making sure the transom is above the water. For sail trim I think a boom vang is important because alot of sail power is lost when the boom lifts, I also ease off the outhaul and downhaul. It is a great feeling and once planing the boat seems to be happier and more stable.

have fun
Shawn

[Roger]

I had to move forward with my 80 pound tank and motor on the transom, but now that I don't have that, moving back to present the flat of the boat to the water would make sense. I do weigh 200+ pounds though, so I have to be careful not to have the bottom edge of the transom start dragging through the water.

I had forgotten about lifting the cb. How high do you raise it, 1/2?

[shawn]

the boat is very sensitive to weight so for me, 170 lbs, and my son, 75 lbs, moving just a foot or so either way can make a big difference. I will have the centerboard all the way up dead downwind to halfway down on a beam reach but I also pay attention to the way the boat is sailing. If it's not gripping the water I will lower the board a little more and vice versa.

Good Sailing
Shawn