Thread: sail size for canoe

Originally Posted by HELLICONIA54

I have a pirogue,17ft long,15" deep and 36" wide at the bottom.It has about 4" rocker and slight flair in sides.It weighs 50Kg's.I am fitting twin outriggers,each float 8' X 6" X 6"boxes on edge.length of beams 6ft.I'm down to making sails,I am also having a mizzen.The sail i want is a boomed,quad sprit.Can anyone suggest a good sail area? I'm looking at cruising with a crew of two.

Hi,

There is known in my country (bibliography) a simple metric formula for small recreational boats:

S [m^2] = L [m] x B [m] x 1.3

For example:

4.5 x 1.2 x 1.3 = 7.02 m^2

For comparison of different boats is another simple formula:

n = ( L [m] x B [m] ) : S [m^2]

"n" is a "size coefficient of sails"

For example:

(4.5 x 1.2) : 7.02 = circa 0.77 (normal - medium)

For comparison, my sailing canoe BETH:

(4.72 x 0.82) : 7.54 = circa 0.51 (racing boat!)

The smaller the size coefficient of sail area, the boat more suitable for racing.

Hoping it will be helpful for you.

Originally Posted by robhosailor

There is known in my country (bibliography) a simple metric formula for small recreational boats:

S [m^2] = L [m] x B [m] x 1.3

For your boat:

L = 17' = circa 5.17 m
B = 36" = 0.915 m

5.17 x 0.915 x 1.3 = circa 6.15 m^2 (circa 66.2 sq ft)

This looks reasonable for cruising (not racing)...

Thank you for that.I was looking at 80sq ft.and around 20 for mizzen,so i'm not too far out lol.Anyway,using polytarp i can cut down the sails if i'm over powered.Thanks again

2.5 times the wetted surface area (sq. ft.) is average, which for a canoe is a tad more then reasonable. 2.4 times the wetted surface would be a better choice for your 3' beam canoe.

Much depends on the type of sailing you want to do, the boat's shape, how much stability you can get from you hull and hiking crew. A sailing canoe that doesn't expect much from it's crew will need a 1.8 - 2.2 qualifier against it's wetted surface. A boat, where the crew will agressivly hike could live with a 2.8 qualifier, even higher if on a trap, but most small boats with moderately high initial stability, like your canoe will have 2.3 - 2.5 as the qualifier.

That's right! This is a very accurate methode designing sail boats, but... There is often difficult to measure of wetted surface on existing boat. I've used formulas shown above many times for comparison many classic small boats - gives good results for classic cruising and racing dinghies than it's useful for HELLICONIA54's purpose - IMHO.

For example - classic German Pirat class (without spinnaker etc.)

5 x 1.6 x 1.3 = 10,4 m^2

Yes she has 10 sq m of basic sail area and in this configuration used in my country for cruising with success!

For example - classic International Snipe class (original - before increasing of sail area)

4.72 x 1.52 x 1.3 = 9.3 m^2

Yes she has 9.5 sqm of sail area in her original version! She was used for sailing education and for recreation for "old boys" in that configuration in my country with success.

For example - classic German H Jolle (and Polish Omega class also)

6.2 x 1.8 x 1.3 = 14,5 m^2

Yes! She has 15 sq m of basic sail area and she is since 194x using in my country as a most popular cruising boat and racing class also.

OK, I have plans (bought by my father in 196x) of small cruising boat:
Józef Grzegorzewski i Biedronka

compare it:

4 x 1.38 x 1.3 = circa 7.2 m^2

Yes! She has 7 sq m of sail area!

OK - check out it for kayaks and canoes:

Sailing canoe P7 - very popular in my country before WWII and up to 196x:

5 x 1 x 1.3 = 6.5 m^2

She has 7.5 sqm and she was known as a very fast, difficult in sailing and chellenging.

Sailing canoe BETH

4.72 x 0.82 x 1.3 = 5.03 m^2

She has 7,54 sqm of total sail area and it is dedicated for experienced sailors as a planing machine - if the gusts are Force 4 I have taken the first reef:


Than - this simple and unaccurate formula is very useful for HELLICONIA54's purpose!


***
EDIT:
Sailing kayak P6 designed for cruising especially:
https://picasaweb.google.com/Radek.R...82932644673762
5 x 0.9 x 1.3 = 5.85 m^2

She has 5 sqm of sail area (and known as a stable and safe) but her original versions from before WWII were training and racing versions with 6.5 sqm of sail area!