Stability question

Jlanni

.
Sep 30, 2015
5
Dovekie 21 Spruce Run
I am looking at a boat with a disp./len. Of 39.05 and a SA/Disp 32.21.
What does this mean and is it stable for myself, wife and two small children? Boat is 21' long.
 
Jul 14, 2015
840
Catalina 30 Stillhouse Hollow Marina
I am looking at a boat with a disp./len. Of 39.05 and a SA/Disp 32.21.
What does this mean and is it stable for myself, wife and two small children? Boat is 21' long.
You are better off telling us what boat it is to get replies on stability.
 

Jlanni

.
Sep 30, 2015
5
Dovekie 21 Spruce Run
It is a dovekie 21 with cat rig and Leeboard. I was also looking at a 17' newport with weighted centerboard. 2 very different boats I know.
 
Jul 14, 2015
840
Catalina 30 Stillhouse Hollow Marina
Dovekie vs. Sea Pearl Tri-21 -- My Experience

By Jim Plourde
Sailing Performance: Off-the-wind, the Dovekie sails well, but the Tri sails faster over-all, although it's not intended for racing. A boat like a Tremolino 21 Tri would be much faster, but at the cost of further complexity and set-up time. However, the Sea Pearl Tri is a very powerful sailor, with fully battened sails totaling 186 sf on carbon fiber masts (this year's model has less). It sails about the same as a good 30' boat, but not as fast as my Laser in planing conditions. The Tri is very stable, is easily balanced with sail trim, always turns through the wind when desired, and is routinely sailed with both sheets cleated. A novelty is being able to move around the boat while sailing on course. In rough water, it is wetter than the Dovekie because of spray coming off the wind-ward ama, which is usually out of the water but occasionally hits a wave top.

Set-Up Time: The Dovekie easily wins here. My observation about sailing is that no one job takes very much time but the total number adds up. A few years ago, I sailed with someone in a Daysailer who took about 1- 1/2 hours to rig it! Early-on, I took 20 minutes or so to set-up my Dovekie, but now I have it arranged so I can be on the water within a few minutes of arriving at a launch ramp. I raise the mast on the water and then attach and raise the sail. Because of the trees and birds, I have to cover both boats at home anyway, so I trailer the Dovelcie using the soft hatch covers-no problem, I don't see them flapping (the hatch covers, not the birds).

At the launch ramp, all I have to do is mount the outboard and remove the cockpit canvas. Undoubtedly, I can improve my set-up time for the Tri with planning and practice, but now it takes 30 minutes or so, although the literature and video claims 15 minutes overall. The amas fold out in seconds either on or off the water. Both sails remain attached to the booms with the full battens attached to the sails and the whole mess is stored in the cabin. I have sail covers, but don't use them since the sails are under cover. Nevertheless, there are two masts to raise and two sails to attach and rig. On my first time out, I wondered, "Does the M marked on the end of one boom stand for main or mizzen?" No doubt the previous owner told me, but I forgot. Overall: The Dovekie continues to be the shallow water camping and simplicity champion. It sails well but the Tri sails much better and is more stable. Again, please keep in mind that I haven't been able to make comparisons to many other boats so if your favorite has been left out, tell us about it.

(Reprinted with the author's permission from The Shallow Water Sailor. For further information about this newsletter write to The Shallow Water Sailor, Kenneth G. Murphy, Editor, 20931 Lochaven Ct., Gaithersburg, MD 20882.)
 

Jlanni

.
Sep 30, 2015
5
Dovekie 21 Spruce Run
The dovekie has a disp./len. Of 39.05 and a SA/Disp 32.21. What does that mean?
 
Jan 1, 2006
7,519
Slickcraft 26 Sailfish
Sail Area/Displacement is analogous to horsepower. But be careful of comparing displacement boats with planning boats. A fat cruising keel boat might have a SA/D ratio of 15 or less. A racer cruiser might be 15 to 19. A racing boat would be 20 or above. I'm not sure of how to apply that ratio to planning boats but a 32.21 is adequately powered.
Displacement/Length is a measure of the boat's heft I guess you could say. Heftier boats being thought to be more stabile.
More later.
 

Jlanni

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Sep 30, 2015
5
Dovekie 21 Spruce Run
I am just trying to figure with 600 lb boat with leyboards and sail area etc. How easy it will be to tip. I believe it is not is notbailing.
 
May 24, 2004
7,164
CC 30 South Florida
I try to stay away from percentages and ratios as they can be misleading. Take two boats with the same ratios, one is a 35' and the other a 21' now take a guess which one will be more stable in storm conditions. If you chose the 35' you are correct by far. Ratios do not quantify stability per se. They are used as an indicator to compare boats which are in the same size and displacement class. Differences should be corroborated in the water.
 
Jul 27, 2011
5,134
Bavaria 38E Alamitos Bay
The dovekie has a disp./len. Of 39.05 and a SA/Disp 32.21. What does that mean?
I sailed and raced a Hotfoot 20 for 3 years in Tampa Bay, FL. The SA/Disp of that boat is 36.03; Disp/len of 76.5 at weight 1000# (i.e., heavier than yours relative to its length). Fractional rig with big a main and 100% jib (overlapping head sail not possible), so not a Cat rig. A planing hull boat as others have noted. Those numbers [of yours] mean it's a light "performance" boat that may depend on crew weight/position and crew skill to handle well. To me, it would not be a particularly good family boat for daysailing w/ young kids. They're great in light air b/c they move; fast downwind in heavier air but everyone has to "hold on!" An unexpected strong gust might put you "on your ear" in less than a heart beat. I can vividly recall more than one 90-deg knockdown in the Hotfoot 20!! If you want "stability" = "comfort" for you, & the wife and kids, I'd reconsider buying a boat like that one, especially if it's your first one. If you want stability with a bit of challenge try a Cal 20 or Santana 20.
 
Jan 1, 2006
7,519
Slickcraft 26 Sailfish
At some point I composed but didn't post another response regarding the 600 lb boat. The gist of it was that at that weight, crew is going to be ballast. And if for whatever reason if too much weight gets caught on the wrong side you will get your feet or more wet. This is in agreement with KG's post that this may not be a suitable family boat. To answer your question I think it would be pretty easy to tip.