Stability criteria of pond sailboats

[George S]

Dear Ancient Kayaker you may be completely right BUT I have cut the wood- so the lower deck is double ended (and the lower frames added.).
The next departure from Baker's lines will be to increase the depth of the hull by an inch and a half to increase displacement so I can increase the amount of lead on the bottom of the to be added fin keel. I am hoping that my calculations will be adequate for the job and that displacement will be about 25 pounds so I will have a stiff boat.
Baker's book "Mayflower & other Colonial Vessels" has a small sent of lines in it. To get a bigger set you need to buy them from <Plimoth plantation> for $25 + s&h. Still that boat is only 11 inches long.

[George S]

The CR914 is 36 inches long rigged as a sloop. The weight is said to be 6.25 lbs., the sail area 658 Sq. inches, the ballast bulb slightly over 4 lbs., I estimate the length of the fin at 9.5 inches, thus the righting moment at 90 degrees heel is approximately 10 inches x 4 lbs or 40 inch pounds.
Similarly, the Tommahawk, a 10 rater, has a mast ht. of 85", a fin of 20", and a lead bulb of 8 lbs. 9 oz. (irrelevantly the loa is 60" and DWL 63", sail area is 1,250 sq. inches) and I estimate the max. righting moment as
20" x 8.5 lbs = 170 inch pounds.
Any similar data would be helpful in designing your own model.

[George S]

Gerr's book was helpful and reassuring. The bottom third of the hull is maybe half done. I am waitinng for better weather to finish fiberglassing the bottom as I do that outside. Then I will add the keel, lower part of the stem and the deadwood and sternpost. I expect to freesail the boat in our local pond so I will not have to worry about RC for now. Next I will add the frames and decks for the upper 2/3rds of the hull. etc.

[George S]

I am looking at Model Yachting (a US mag.) issue 155 and at p. 21 Russell Potts speaks about vintage British models. He says the 1730 tonnage rule produced very narrow, deep hulls which were heavily ballasted and came in 5 ton,10 ton and 20 and 40 tonners with model weights from 80 pounds down to 20 for 10 tonners. but I cannot tell from the photos how long the hulls are.
Shifting to stability criteria, it is hard to find hard data on many boats. The Laser is discussed in issue 154 where it notes that the fin is 16 inches long and has a four pound lead bulb. Thus I deduce that the maximum righting moment may be about four pound feet. The boat's tall narrow una rigs range from 949, to 710 to 600 square inches.