30'O'Day top speed??

[Captainron1]

Hello everyone, Can anyone tell me what sort of speed I should get out of my 30' O'day?? I have new sails, head sail is a 150. I realize the sail trim is important, but with everything working perfect how fast will this baby fly?? I'm really enjoying my yacht True North, now to make him work at top speed.
Many Thanks
Ron

 

[SailingCal21]

I calculate a theoretical hull speed of 6.77 knots using Carl's Sail Calculator ( http://www.image-ination.com/sailcalc.html ). That's a good place to start.

 

[Captainron1]

O'day top speed

I calculate a theoretical hull speed of 6.77 knots using Carl's Sail Calculator ( http://www.image-ination.com/sailcalc.html ). That's a good place to start.

Thanks for the info, According to my land GPS I am getting 12 to 13 KM's which is close to 6.49 knots and your calculation.
Many Thanks
Ron

 

[jibes138]

for a simple calculation use 1.34 x the square root of the LWL

 

[SailingCal21]

Karma's hull speed is 7.2, I've seen 8.5 on my GPS whilst sliding down the backs of swells in a fresh breeze. I've often wondered about the accuracy of a GPS when there's a lot of boat motion on different axis.

 

[jibes138]

GPS is just giving you an average speed based on current position versus previous position based on the time interval it uses to calculate. A knotmeter gives you instantaneous speed but frankly they aren't worth the hole in the boat they made to install them. I hit 12 knots surfing down waves and dead down wind with just a handkerchief of headsail up when sailing down from Ct. in a storm. Apparent wind speed was in the mid thirties from 180 degrees. That lasted for about 2 days. So the boat will go faster than hull speed in the right conditions. The hull speed is based on pushing a displacement boat in the trough created by the bow and stern waves, basically the speed those waves move through the water. To go faster you need to push the boat up on top of the bow wave, very much energy required to do that for a 11,000 pound boat. Surfing down waves you overcome that constraint.

 

[Odaysailer]

I hit 12.1 knots surfing down waves off the California coast in my O'Day 272! Because of the wing keel's inherent inability to prevent side-slipping, my Wednesday crew refers to the boat as "Slo Mo"! I wish they had been aboard for this trip!

 

[the_alpine]

I push 6.5-7.5 on my 1987 302 regularly. As stated upthread, I've also clocked over 12 surfing down 25 footers.

 

[colinhulse]

30's top speed

My 30 O'day on Lake St.Clair tops out at 7 knots.

 

[wes carroll]

How hard is the wind blowing?

 

[colinhulse]

30 o'day.

Not that hard, 15 knots. I sanded the bottom paint off last year. Over 150 lbs. Coated with 2000 and bottom painted with VC-17. It added a knot to the boat. I can see the difference when running the engine slowly in calm waters. It moves faster with that 25 year layer of crap gone.
I have the factory main and a 150 flying. I have a Gamin chart plotter and a separate GPS in the cabin. I get 5kts knots easy . 7kts is work but she does it.