The Offshore Voyaging Reference Site

Sail Heel Angle

The late, great—I know it’s a cliché but he was—Buddy Melges, when asked how to drive a boat well upwind, would say that the secret is keeping the angle between the headstay and horizon constant.

For us lesser helmspersons, an inclinometer makes this way easier.

I was just about to fit one to our J/109 when I realized that the smart compass I installed last winter also measures heel angle and sends that out on the NMEA 2000 network, so it was just a matter of moments to add it to one of the cockpit readouts.

Once the boat is fully powered up, sailing a constant heel angle through the puffs and lulls is a way faster and more comfortable way to helm upwind than just following the jib telltails.

Excessive heel is also a not-so-subtle hint that it’s time to reef.

Nothing more than 20 degrees is fast on the J/109, flatter with a full crew on the rail.

The M&R 56 is fastest up wind at about 23-25.

Boats that are not as easily driven will need more heel, and full-keel boats with a lot of wetted surface are often fastest at high angles—as much as 35 degrees.

That said, many people, particularly those new to sailing, let the boat heel too much.

Anyway, every sailboat should have a way to display heel angle. If your autopilot compass does not have this feature, a simple inclinometer will do.

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James Sarrett

I have always spelled it “heel”, and merriam-webster seems to agree with that spelling. is heal a common spelling in the northeast?

Colin Speedie

Hi John

20 degrees is about right for modern, beamy boats, I’ve found. Once past that the underwater shape starts to tell and not in a good way.
Reef early, reef often!

John Cobb

I was thinking about buying one of these

It outputs pitch and roll to the network so I guess you could read the roll as heel angle?

Pete Running Bear

Agree that heel angle readout is great, as is rudder angle. Your compass should have trim too which is interesting both for long term and short term fore/aft weight distribution. Obviously the boot stripe will help with the former.

Michael Fournier

Great article. Key is knowing your boat. Learned very early back at summer camp sailing lasers as a kid it may seem faster sailing with the rails in the water but the leeway increases and your added rudder to over come weather helm slows your actual over ground speed. Same can apply to those rule bending IOR boats with big over hangs designed to heel early will sail faster as the water line increases as they heel but the optimal angle range is narrow as weather helm will increase and then leeway and drag starts to slow you down again. (Not to mention risk of a broach)

Jean-Louis Alixant

It is indeed about “knowing your boat”, and that can take time. One way to cut down the time and effort is to use the output of a VPP: that will provide the theoretical optimal Heel angle for the full range of TWS and TWA pairs. It usually provides a very good starting point.
If you don’t have the data for your own boat, lookup the information for similar ones, they will provide useful trends and indications, which you can then adjust and refine.
If you know your boat well, VPP outputs can still provide a healthy challenge for established habits and may point to performance opportunities.

Philippe Candelier

I discovered that those inclinometer have also a great psychological effect: once you can put a number on the heel angle, suddenly for most young crew (young to sailing a monohull) life is good. No more anxiety about 15-20 degrees heeling.

Alastair Currie

I bought the Sun Coorporation’s Lev-o-gauge SR model and stuck it on the bulkhead facing aft to my helm position. It works great, is damped very well and nice and clear. Downside it is a bit industrial looking. For my Rival 41C at 41′ LOA, 12.2′ beam and 5.9′ draught, 10 tonnes, deep forefoot and encapsulated fin, I find around 30 degrees I have too much weather helm, digging in the side decks and just a lot of drag. I tend to sail upwind around 25 degrees max and get all the drive I need.
It is a neat tool to use, which gives that reference number to what was gut feel angle anyway. I have been using it for about 3 years now.

J Peter Forte

On my Sabre 34, the salon/cabin top had beveled sides, and I am told that the ideal sailing heel was when the beveled sides were horizontal.