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Go Back   SailNet Community > Out There > Cruising & Liveaboard Forum > Desired features vs. boat capabilities
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Thread: Desired features vs. boat capabilities Reply to Thread
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Topic Review (Newest First)
12-14-2011 02:25 PM
MarkSF
Quote:
Originally Posted by Minnewaska View Post
They are not. For every definition I've seen, there are dozens of examples of boats that fit one definition but have successfully completed voyages in another category. I think defining the skipper is a better way to define the boats capabilities.

This boat crossed the Atlantic. It's 13 ft long.

Edit: this is an Internet linked photo. If anyone knows how to resize it smaller, please PM me and I will fix it. Thx.

This one crossed the North Sea. A Wayfarer centreboard dinghy.

Redirect Notice

However, I think most of us would be unhappy with the safety margin Frank Dye voyaged with.
12-14-2011 01:21 PM
killarney_sailor I think that everything being equal (like good designs in both cases), which may or may not be the situation, a canoe stern should not matter much to how the boat handles. I think it is an aesthetic decision, Be aware that the rounded, typically narrow shape does take away some practicality since you lose valuable storage space or living space (depending on the design), and will have more issues with mounting davits, an arch for solar panels, vane steering, having a walk -through transom which makes dinghy access and swimming easier. All part of that grand series of compromises that comes into play. Of all of these, we only have the accomodation issue (aft cabin) and self-steering (the manufacturers generally can make a mount for a canoe stern); but many newer cruising boats have open transoms and often davits and arches. You pay your money and take your choice.
12-13-2011 09:52 PM
Dean101 Personally, I've been taking all these ratios with a grain of salt. I'm sure that other factors play into the final amount of stability any boat has. I just consider them to be a general indicator. What is your opinions on the shape of the stern? Some of the round stern boats as well as the double-ender's appeal to me. I'm curious if they handle differently in a following sea.
12-12-2011 07:28 PM
mitiempo That wasn't my point - the usefulness (or lack) of the capsize formula was.

A less stable boat, if heavier for its length, has a better capsize ratio.

In Europe there are many boats that are light and rated Cat 1 for offshore use.

A good offshore boat doesn't have to be heavy.
12-12-2011 07:18 PM
killarney_sailor And if I am considering a Pogo 1050 for extended cruising I will remember this. The OP was asking about boats of a more conventional type and not ones like this that would useless for extended cruising.

Hopefully more helpful advice - the prevailing wisdom on Oz (heard independently from several people with extensive cruising backgrounds) is that black bottom paint attracts (amorous?) whales. Can't comment personally since I am a blue paint kind of guy.
12-12-2011 02:22 PM
mitiempo Yes, if one boat is 200 D/L and another 290 D/L there is a difference - the one at 200, assuming the same overall length, could well be heavier.

One of the examples of the capsize ratio being totally ineffective is the Pogo 10.50.
7937 lbs displacement
2425 lbs ballast (31%)
Ballast on the bottom of a 9' foil - about as low as it can get on a boat 35'
long.
The capsize ratio for the Pogo is 2.57
12-12-2011 02:10 PM
killarney_sailor
I said these were approximations and not exact indicators

Quote:
Originally Posted by mitiempo View Post
Killarney

Capsize ratio is based on 2 numbers only - beam and displacement. If you take a boat - any boat - and add 1000 lbs to its deck, mast, or cabin table it has a much better capsize ratio. How can that not be meaningless?

Here's the best link I have seen for all ratios pertaining to stability, hull speed, D/L ratio and others. Capsize Formula It is the US Sailing site.

For many of these calculations to be used properly you have to know how they are derived. D/L ratio is another suspect ratio when used to compare boats of different types - many think a low D/L ratio means a light boat but not really.
I understand the derivation (and meaning) of these values as I used to teach math. For your comments about Capsize Ratio, there are some interesting comments about the vertical position of the center of gravity to the left of the formula calculating box on the US sailing site that suggest that this is a relatively unimportant value in preventing capsize but or more significance in recovering from capsize once it happens. In any case it is a useful measure when nothing more is available.

The D/L ratio again is only a start and the value is affected both by displacement and waterline length - I have never seen what this ratio would be for one of the old (think it was) Universal Rule boats that had incredible overhangs. On my Bristol the LWL is relatively short but once you actually start moving the stern squats and you gain probably 18 inches of waterline. When someone looks at this ratio, it does not matter very much if one boat is 290 and another 270, but if one is 290 and another is 200 it does indicate something different.
12-11-2011 04:32 PM
mitiempo Killarney

Capsize ratio is based on 2 numbers only - beam and displacement. If you take a boat - any boat - and add 1000 lbs to its deck, mast, or cabin table it has a much better capsize ratio. How can that not be meaningless?

Here's the best link I have seen for all ratios pertaining to stability, hull speed, D/L ratio and others. Capsize Formula It is the US Sailing site.

For many of these calculations to be used properly you have to know how they are derived. D/L ratio is another suspect ratio when used to compare boats of different types - many think a low D/L ratio means a light boat but not really.
12-11-2011 04:10 PM
killarney_sailor As was pointed out, that website only uses calculations based on generally available data like LWL, Displacement, 100% fore triangle sail area, etc. I would disagree that it is "almost meaningless". More accurate measurements can be obtained empirically but those are not available for most boats so something (an approximation) is better than nothing.

About boat speed, it is not entirely a relative thing. You can get a PHRF rating for many, many boats and that will tell you something (far from everything). Short of really top-level racing which has become quite quantitative in its approach is a largely qualitative endeavor. As to speed, it is better to go fast than slow if it can be done in comparable comfort and safety. It takes all types though. We met a couple cruising on a J40 and then did Norfolk to BVI in 8 days when it was really honking. This is a good thing since you take less of a beating and have more time where you are going. We met a man in Fiji who was cruising on an old Pearson 36 and only used a 90% headsail (no matter the conditions - and I don't mean with the main - he only used the jib). For his planning he used 50 miles a day for planning purposes in the trades - we use 120 and rarely would be less than 100 and can do in the 160s and 170s fairly often. His comment is that he has lots of food and water on board along with lots of books so he doesn't care how fast he goes. As I said, all kinds.
12-11-2011 11:19 AM
Dean101 Killarney, I checked out the website you suggested. Very handy to be able to compare boats quickly. I completely agree with you about the need to take the entire boat into consideration and I've been trying to do just that as I research boats. The criteria I've been using so far as pass/fail qualifier for entry onto my short list of choices are;

Length 32' to 40' with 36' being ideal, full or fin keel, cockpit not overly large, companionway raised to keep out water, small opening ports, no large windows, main sheet not obstructing cockpit, 6' 2" min. headroom, decent galley preferably L or U shaped, must have nav station, good reviews, and generally available under $40k - $50k.

I didn't mention a rig and although I'm thinking a cutter sounds like the best choice, I'm flexible on that. I'll be living aboard, initially coastal cruising the eastern U.S. and throughout the Carribean. A trip to Europe and the Scandinavian countries then it's off to the Pacific. I want to visit S. America and cruise the coastline up to the Aleutian chain, visit Asia and the south Pacific.

So yes, looking at the overall boat is important but I need to understand what I'm looking at so I can make an informed decision as to whether what I'm looking at will keep me safe and comfortable while doing all that.

@ Mitiempo - Until I checked out Killarney's suggested site I've been using cruisingresources.com to look up ratios and factors. Are there any other sites you can suggest? I'm not really clear on what information is needed to breed accuracy into these numbers and I take them all as a general assessment rather than difinitive information.

@ Joelsandra - Feel free to criticize away. I'm beginning to think that maybe I'm going at this the wrong way with the list idea. I agree with you about the books and some of the equipment people say you need. My intent with this thread was not to create yet another list of electronics or spares needed for offshore trips but rather to gain some knowledge as to what makes a boat the right choice for its intended use. We hear things like a comfortable motion, windward abilities, and stability. I want to know what makes a boat have those things because, frankly, I don't want to take the sellers word for it.

People write about a boat being slow but never say what they're comparing it to. When someone says a boat lacks windward abilities, does that mean it can't point higher than 45 degrees off the wind? How high does a cruising sailboat need to point? Sometimes I think that racing plays a big factor in what people think about cruising boats. I think that for some people performance is the sum of speed, maneuverability, and pointing high. My opinion is that performance is the ability of the boat to do what it was intended to do. By that standard, if I want the boat to carry a lot of weight, have plenty of storage, get me around the world safely, and be able to come through a gale smelling like a rose, then a Westsail 32 is a high performance boat! Now let's see what kind of reaction that particular statement will inspire!

You can't really blame the marine outlets since that's what they are in the business of doing, or even the people making the lists since those things are what they feel comfortable with. Even proponents of a certain type of rig are expressing their personal choice. What works for one may not work for another. Slocum changed his rig more times than some people change their underwear, so where does that leave us?
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