HELP. Need LCG Data for a dinghy...

[Clinton B Chase]

expressed as a % of length of boat for an existing proven set of lines for a open sailing dinghy glued construction about 14' 10" x 5' 10". The important thing is that the design is similar to mine. Some plans indicate the LCG/LCB. Then it is a matter of getting the position as a % of LWL. If it is not indicated I guess the only other way is to take the curve of areas for the hull below water line and find the geometric center. This is an unballasted, C/B sailing dinghy so I realize it doesn't have to be dead on...maybe there is a rule of thumb I can use for now.

Thanks.

Cheers,
Clint

[Varna]

Hello Clinton,
I've found most modern sail boat CB/CG to be in 55% range in plans I've studied and measured to learn boat design by books and plans over the years. I have measured using both planimeter and graph paper squares, and Simpson's formula and/or cardboard cutout method. 53-56% Range is what I've seen. I'm not sure about this but an all-out planning dinghy may move the CB aft a bit more, but I think you are designing a all around day sailer and family boat. I have uffa fox palns for his 16' lively and several of his 14', and Gartsides 14' Swansong- very close to your parameters.
You asked about beam in another thread. Since your B/L is similar to swansong I will mention that Swansong -while beamy at the topside dimension- has a narrower B/L at lwl - 13'6" x 4'3" - the sections are very round and slack- no tight bilge turn. Also makes clinker plank easy, and gets crew weight outboard. This is a boat that I feel would be a fun and versitile sailer.

[Clinton B Chase]

TX for the great info...yes, my 20' sailboat that I had drawn up with at WBS with Paul Gartside had a ~a 56% LCG...so it looks like I am OK.

About the beam...tx for bringing up the w.l. beam vs. beam at the rail...I need to mull that over...while those slacker sections may be better for all around dinghy sailing w/ a family it also reduces the width of the boat inside at the floorboards and space is nice...this is what I love about design the constant trading off and thinking about things back and forth...finding the balance. Check your PM's I have a message there too.

Cheers,
Clint