SailNet Community - View Single Post - boat check - to Jeff H and others
View Single Post
Old 08-27-2003
Jeff_H's Avatar
Jeff_H Jeff_H is offline
Join Date: Feb 2000
Location: Annapolis, Md
Posts: 6,761
Thanks: 5
Thanked 119 Times in 94 Posts
Rep Power: 10
Jeff_H has a spectacular aura about Jeff_H has a spectacular aura about Jeff_H has a spectacular aura about
boat check - to Jeff H and others

I would like to touch on Bob''s well written comment. I am backing into this a little differently than Bob and therein lies the difference in our approach. I prefer to start by trying to select a boat that is smaller than the biggest boat that I am comfortable single-handing in a wide range of conditions. At 5''-9" and 165 lbs, I am not a very large person. Although I am in pretty fair shape, after sailing boats of a wide range of displacements, I have concluded that my body strength and the physical endurance of my 53 year old body limits the size boat that I can single-hand comfortably to somewhere in the range of 12,000 to 14,000 lb displacement. It is not that I can''t singlehand a heavier boat, but I find that the loads go up substantially with displacemnt so that I am ground down more quickly by a heavier boat in heavier conditions. As I noted before, it really displacement more than length that determines carrying capacity, maintenance costs, sail size, the loads on various components and ease of handling.

Now then, in my case, starting with something less than 14,000 lbs as an ideal manageable displacment for myself, this would point me at boats as small as 30 feet or as large as 40 feet. The reality is that all other things being equal the longer boat will have an easier driven hull and so would get by with less sail for a given condition. This becomes very critical in rough going. Beyond that, all other things being equal, the longer boat of the same displacement will actually be be less likely to "beat you to death" than the smaller boat of the same displacement

Normally a heavier boat for a given length would be thought of as a moderate to heavy displacement boat. From my way of thinking what would normally be called a moderate to heavy displacemnt boat is actually a short boat for its displacement. I know that this appears to be difference without much of a distinction, but again as I have argued here before, I think this comes down to how you define the size of a boat. If you define the size boat that you can handle by length then the heavier boat for a given length would seem more comfortable. If you define the size of a boat by weight, then the longer boat would be more comfortable.

In reality the longer boat for a given weight will generally offer more stability than the shorter boat of the same length. This occurs for a number of reasons but in a general sense the longer boat will generally have a shallower canoe body than the shorter boat of the same displacement. This raises the vertical center of bouyancy (VCB)while allowing the vertical center of gravity (VCG) to remain at the same height. As we all know one of the key determinants of stability and motion comfort is the relationship of the VCB and the VCG (the lower the VCG is to the VCB the more stability the boat will have.)

This becomes even more evident in heavy conditions when the more easily diven hull of the longer boat of the same weight is able to get by with less sail area to achieve the same VMG.

There is one more point here, not all light displacement boats are created equal. A lot of prejudice against lighter boats comes from sailing on early or poorly designed lighter boats which I must admit are more common out there. By and large early light displacement boats came from two different model types based either on the IOR type form or a ULDB (so called sleds). The IOR type form produced boats that had a very high VCG and which depended on a lot of form stability and crew weight on the rail. As a result they were tender and very uncomfortable in a seaway. The ULDB were optimized for downwind work and so were short on stability. Since the 1980''s more well rounded lighter boat type forms have appeared and these offer very high stability and motion comfort for their displacement.

There is one last point on stability. Short boats for their displacement (moderate to heavy displacement boat) often gain their weight in components located in other than stability producing locations. They are often short on stability relative to the boat''s displacement. This is often compensated for by carrying smaller sail plans (lighter boats often carry SA/D''s in the over 20 range while heavier displacement boats typically carry SA/D''s in the low teens). This means poorer performance in light air, and the use of larger, more difficult to handle, less efficient sails in these condition but as referred to above, in really heavy conditions a certain amount of drive is required to safely sail a boat of a given drag. The higher drag of the shorter boat of a given displacement requires more drive to push it through rough conditions. It is threrfore in really heavy going that the reduced stability often found in a shorter boat of a given displacement becomes more of a problem for the singlehander forced to carry more sail than the sailor or boat can comfortably handle.

Anyway as bob-m notes, "YOU are the only one that can answer which is more important to you. It would help if you define your objectives and what you are looking for more concisely."

Reply With Quote Share with Facebook