Angle of Heel - Does more mean less speed?

[Max Treece]

While attending a local Sail Clinic for Lightnings and J22s this weekend, the point was made that boats should be sailed flat with no heel. I have always tried to keep the rail out of the water on my CD25 but always thought that its best speed was when heeled over to about 20-25 degrees. Our instructor did conceed that in very light winds, it was good to put the crew on the leeward side to force a little heel to overcome gravity of slump sails.

For all the folks that race the Cape Dorys, what considerations do you give to the heel of the boat. Do you have a certain angle that you believe your boats sails best and at the best speed?

Thanks for your thoughts?



metreece@duke-energy.com

[Larry DeMers]

Lightnings are an essentially flat bottomed (planning) boat compared to the hull of the cape dory (which is a displacement hull..big difference). What this means is that the Lightning has tremendous initial stability but no reserve stability after heeling past a certain point, so it needs to be sailed nearly flat for it's hull shape, with the hull just breaking out of the water on the windward side, to minimize wetted surface area.

Cape Dory's have a rounded chine and bilge, which encourages a 15-20 deg. heel (max.) which then places the boats cheeks in the water, increasing the LWL, which raises the max. speed that she can sail at (as a displacement boat).
For this reason, Cape Dory's should be sailed at 15-20 deg. heel, no more. If you increase the heel past this point, you remove too much of the sail from the wind thru heeling..the wind simply slides up and off of the sails top. Maximum speed is obtained while the heel angle has maximized the LWL while still projecting the maximum sq. ft. of sail possible. Any more heel, and the sail area projected decreases, slowing the boat down.
A way to judge this is the angle of the coach roof. Sit up there while underway, and when it is flat, the cockpit will be heeling 15-20 deg.

Cheers,

Larry DeMers
s/v DeLaMer
Cape Dory 30
Sailing Lake Superior -ahh, but for the snow and ice-

While attending a local Sail Clinic for Lightnings and J22s this weekend, the point was made that boats should be sailed flat with no heel. I have always tried to keep the rail out of the water on my CD25 but always thought that its best speed was when heeled over to about 20-25 degrees. Our instructor did conceed that in very light winds, it was good to put the crew on the leeward side to force a little heel to overcome gravity of slump sails.

For all the folks that race the Cape Dorys, what considerations do you give to the heel of the boat. Do you have a certain angle that you believe your boats sails best and at the best speed?

Thanks for your thoughts?

demers@sgi.com

[Stan W.]

In response to both your messages, also remember that increased heel CAUSES increased weather helm. As the sail plan goes more horizontal, it acts as a lever twisting the boat into the wind. Also the shape of the wetted surface becomes more asymmetrical which adds to the effect. This is a big reason why you should reef early and often.



smwheatley@capecod.net

[Eric]

Every boat is different, is the short answer. CD' should probably have a 10-15 degree heel to perform best (because of the full keel/rounded bottom). Other boats, however, are better off flat. That's especially true of planing boats. I used to race Sunfish and Lazers and would go for a slight heel to windward on those boats. Especially downwind. IN the Sunfish it was a matter of keeping less surface area in the water and keeping the odd rig upright. As for our CDs, I think the most important thing is to trust your instincts. If you have a big weather helm (or spill your drink), you are probably heeling too much.

While attending a local Sail Clinic for Lightnings and J22s this weekend, the point was made that boats should be sailed flat with no heel. I have always tried to keep the rail out of the water on my CD25 but always thought that its best speed was when heeled over to about 20-25 degrees. Our instructor did conceed that in very light winds, it was good to put the crew on the leeward side to force a little heel to overcome gravity of slump sails.

For all the folks that race the Cape Dorys, what considerations do you give to the heel of the boat. Do you have a certain angle that you believe your boats sails best and at the best speed?

Thanks for your thoughts?

[Don Carr]

My observations of heel relative to boat speed on the CD25 is this. I thin you are correct on the 20-25 degree heel. I have done some informal testing on my boat and found that up wind (about 40 degrees aparent wind angle) in 12-15 knots about 27 degrees (measured by inclinometer) with a 150 genoa actually maximizes the speed at somewhere between 4.1 and 4.5 knots.
On the off-wind beam/broad reach about 15-20 degrees maximizes the speed at around 5.0-5.5 knots. I believe we had John Laton's boat Happy Daze up to 5.3 knots in about 12 knots close reaching and heeled at about between 23-27 degrees. John may want to comment.
Are there any CD25'ers interested in developing polars for the boat??
Might be interesting.

FWIW.

Don Carr
s/v Lolita CD25
Noank, Ct.



carrds@us.ibm.com

[Sean]

As I am learning...regarding your post, Don. What are polars?

Thanks,

Sean
previous owner of CD TY, s/v Epiphany
beginning search for next CD
Riverside, RI

[Don Carr]

Sean; Polars are plotted windspeed , wind direction (true) over boatspeed. So you go out and under controlled wind speed (yeah right) conditions, sail your boat with optimal speed on different headings and plot the speed points. Then connect the dots and you will have a good idea of target boat speed given any wind speed / true wind angle. Polars can be derived mathematically based on boat measurements and generally are initialy created using Velocity Prediction software and validated through actual performance.



carrds@us.ibm.com

[sean]

Sean; Polars are plotted windspeed , wind direction (true) over boatspeed. So you go out and under controlled wind speed (yeah right) conditions, sail your boat with optimal speed on different headings and plot the speed points. Then connect the dots and you will have a good idea of target boat speed given any wind speed / true wind angle. Polars can be derived mathematically based on boat measurements and generally are initialy created using Velocity Prediction software and validated through actual performance.

Tha

[John Laton]

I just today saw this post so I'm a little late in my comments.. Capt Carr has a good memory.. His recounting is correct. It was about this time last year when the good captain was so gracious as to break me in on a 2 day jaunt from Point Judith RI to my home port of New Haven CT. I gained a wealth of knowledge and respect for the CD and it's forgiving nature. Just don't tell Don I called it a "tiltometer" or he won't let me act but as ballast on his racing Team..

Capt JT
S/V Happy Daze
CD25 #288
New Haven, CT

My observations of heel relative to boat speed on the CD25 is this. I thin you are correct on the 20-25 degree heel. I have done some informal testing on my boat and found that up wind (about 40 degrees aparent wind angle) in 12-15 knots about 27 degrees (measured by inclinometer) with a 150 genoa actually maximizes the speed at somewhere between 4.1 and 4.5 knots.
On the off-wind beam/broad reach about 15-20 degrees maximizes the speed at around 5.0-5.5 knots. I believe we had John Laton's boat Happy Daze up to 5.3 knots in about 12 knots close reaching and heeled at about between 23-27 degrees. John may want to comment.
Are there any CD25'ers interested in developing polars for the boat??
Might be interesting.

FWIW.

Don Carr
s/v Lolita CD25
Noank, Ct.

Laton@ynhh.com

[jonathan]

Yes. It does matter, depending on how much. On my CD31, the optimum speed is to have the rail just kissing the water occaisionally going to windward. A buried rail all the time means the boat is stalled, which can happen easily here on San Francisco Bay with 25 knots the norm in summer. I don't know CD25's. If you can tune against another CD 25, that will tell you. Or look at your wake. If you are leaving a big trail, you have too much weather helm and too much sail.

Lightnings and J22's have a significantly different hull shape. I think CD's which are more designed to have a longer water line, and thus greater hull speed, with a certain amount of heel would be somewhat different.



jerb@plawp.com