salt water vs fresh water bouyancy in boat plans

[blackdaisies]

I was just peeking in to ask about the water line and balance change from fresh water to salt. Will it have a major effect on a boat usually sailed in fresh water?

Salt water is denser, weighs more, and displaces less, so a boat built for fresh water sailing will act differently on salt water?

Thank you for your time.

 

[Ad Hoc]

If you're talking about a 300m supertanker...yes
If you're talking about a small dinghy...no.

 

[blackdaisies]

It's a small boat, but I was wondering what a difference it would make. Even small ones with ballast or keels would be effected by a relevant change. I was wondering if that would be needed in choosing a design.

 

[Ad Hoc]

The difference, if a small boat, is so minor it is not worth even worrying about. In reality you wont notice any difference at all, even though there is technically a "difference".

 

[lewisboats]

The difference is 1.6 lbs/cu ft of displacement. say 16-32 lbs in a smallish boat. total difference in draft is in the order of an inch or less. You'll float a bit higher in salt than in fresh...so bring another case of soda or whatever.

Steve

 

[ned L]

I can tell you that I remember a 'well previsioned' 46' 1950 Chris Craft floating maybe an inch lower on her lines in fresh water than in salt water, so as said, not a big differance.

 

[blackdaisies]

Is it better to be higher than lower in a design? I would think I would want to build for fresh water and be higher in the water than for it to be lower.

 

[Brent Swain]

Many BC fishboats with greedy skippers have been loaded to deck level in salt water. They do OK until they hit the freshwater of the Frazer River , then they sink like a stone. Not a problem ,unless your decks are awash in salt water.
Brent

 

[blackdaisies]

I'll remember that. You never know when that may come in handy. Don't be a greedy sailor in fresh water.