Comfort and capzie ratios

[glcalahan]

Hello,

I didnt know which forum to post but, here goes.

I have been live aboard/sailing since late '70s and 98% was Intercoastal and early a lot of racing.

Now at 69 have spent 2 1/2 rebuilding a 1972 Pearson 33. I planned to leave Jan for 6-8 months the Bahamas and sadly I will be tweaking my destination points. That being said....my question.

I was told by a sailing FB group that the P33 is a coastal cruiser. I get that, however don't fundamentally agree. Given a good weather window, a sound (everything in the boat is new) and prudent, cautious attitude will I be okay??? Yes....anything can happen....

I have been following 2 YT video bloggers that are on similar boats. 1st is a 1972 Pearson 36 and the 2nd is a 1971 Pearson 35.

Here are Saildata's stats:

Pearson 36 Comfort 27.02 Capsize 1.86
Pearson 35 Comfort 33.41 Capsize 1.70
Pearson 33 Comfort 28.15 Capsize 1.81

I do realize numbers are just that...numbers. The P36 and P35 seem to be doing fine offshore. The P36 is in Nova Scotia after extensive Carribean Cruising now heading to England. The P35 cruised also thruout Caribbean and (I think) currently in Dominican Republic.

What do these numbers mean? I have not been able to find anyone who I believed convinced me they really knew.

To me....the numbers are so close, I feel I will be fine. Again....I understand there are seamanship and weather variables.

Thanks.....go!

[Paul L]

I think the numbers are pretty much irrelevant to what you are planning. The trip to the Bahames is coastal cruising. You never need to be out more than 2 days, and more likely only one. So if you bring along a decent source for weather, you should not be dealing with anything more than a squall while offshore. Inshore at anchor you will have some windy times when cold fronts come through, so have a good anchoring setup. This is assuming you will be out of there during hurricane season.

[GordMay]

Ted Brewer Presents A Primer on Yacht Design
The Numbers (More Than You Ever Wanted To Know!)
➥ https://www.tedbrewer.com/yachtdesign.html

ie: “COMFORT RATIO (CR):
This is a ratio that I dreamed up, tongue-in-cheek, as a measure of motion comfort but it has been widely accepted and, indeed, does provide a reasonable comparison between yachts of similar type. It is based on the fact that the faster the motion the more upsetting it is to the average person. Given a wave of X height, the speed of the upward motion depends on the displacement of the yacht and the amount of waterline area that is acted upon. Greater displacement, or lesser WL area, gives a slower motion and more comfort for any given sea state.

Beam does enter into it as as wider beam increases stability, increases WL area, and generates a faster reaction. The formula takes into account the displacement, the WL area, and adds a beam factor. The intention is to provide a means to compare the motion comfort of vessels of similar type and size, not to compare that of a Lightning class sloop with that of a husky 50 foot ketch ...”

[thomm225]

Those are all good capsize screening formula numbers.

I believe after all the destruction of boats in the 1979 Fastnet race it was recommended boats have a 2.0 or lower to race

Something of this nature

A Contessa 32 was able to sail thru the storm of the '79 Fastnet and it's capsize screening formula number is 1.80

It has an angle of vanishing stability (AVS) of 155 degrees which is very good also

[TrentePieds]

Quote: "What do these numbers mean?"

Short answer: Not much!

Longer answer: Both of these "ratios" have been dreamed up by yacht designers in order to give the glossy mags editorial copy to fill the empty space twixt advertisements. They are sort of an "in joke".

My opinion is that when thinking of cruising, considering a boat in isolation from that boat's skipper misses something very fundamental: No boat, however good in technical terms, and in terms of quantification of design parameters, can keep a clunky skipper safe. And the corollary: A GOOD skipper can always keep a clunky boat safe. Boat and skipper are a complementarity - an entity - and must be considered as such.

We'll skip the treatise it would require to explain why. Just know that your Pearson is a well designed, well reputed boat, and if you are a good skipper you have no need to look for anything "better". Never mind the "ratios". As I said, they are really just an "in" joke. Focus on your skippering skills, and you'll be fine!

TrentePieds

[Ken Z]

Pearson is a good boat, granted a production boat but a lot of thought has gone into the boats details. always wfw, wait for weather, check for mast corrosion at the base, go for it .... they werent skimpy on glass in 1972.

[barnakiel]

To me, comfort ratio is pure BS.


Maybe the guy who invented the metrics had interest in which boats pop up as comfortable? Maybe he was a boat designer? Murky waters, useless ratios.


I would not say the above if not for our boat having very high comfort ratio yet somehow being very tiring on a passage.


I have sailed plain Bava and Bene boats, with drastically low comfort ratios yet somehow delivering absolutely delightful ride compared to our own boat.


The capsize ratio I will not dispute. Our boat capsized once and came back. Also came back from a full wipe out.



As for your specific boats: you are wasting your time with pen and paper approach.


Find people who own them, do some sailing. Then you will know if the boat has the comfort you require. Hopefully you will never learn if her capsize ratio was good enough.


Also mind with such small boats any serious amount of cruising gear will seriously shift the base figures.



Cheers,
b.

[Shenandoah52]

Originally Posted by Ken Z

...go for it .... they werent skimpy on glass in 1972.

This is so true. Back in those days we would buy resin by the 55 gallon drum and mix it in buckets like it was free it was so cheap. We had a pile of cured resin at one boat shop I worked at that must have weighed several tons. Any resin left over from the bucket you had just mixed was poured on that pile.

The only thing we worried about at the time was not getting the exothermic reaction to the point it would catch the whole pile on fire. We'd regularly smoke the paint right off the coffee cans we used for mixing.

[MJH]

Originally Posted by glcalahan

Hello,

I didnt know which forum to post but, here goes.

I have been live aboard/sailing since late '70s and 98% was Intercoastal and early a lot of racing.

Now at 69 have spent 2 1/2 rebuilding a 1972 Pearson 33. I planned to leave Jan for 6-8 months the Bahamas and sadly I will be tweaking my destination points. That being said....my question.

I was told by a sailing FB group that the P33 is a coastal cruiser. I get that, however don't fundamentally agree. Given a good weather window, a sound (everything in the boat is new) and prudent, cautious attitude will I be okay??? Yes....anything can happen....

I have been following 2 YT video bloggers that are on similar boats. 1st is a 1972 Pearson 36 and the 2nd is a 1971 Pearson 35.

Here are Saildata's stats:

Pearson 36 Comfort 27.02 Capsize 1.86
Pearson 35 Comfort 33.41 Capsize 1.70
Pearson 33 Comfort 28.15 Capsize 1.81

I do realize numbers are just that...numbers. The P36 and P35 seem to be doing fine offshore. The P36 is in Nova Scotia after extensive Carribean Cruising now heading to England. The P35 cruised also thruout Caribbean and (I think) currently in Dominican Republic.

What do these numbers mean? I have not been able to find anyone who I believed convinced me they really knew.

To me....the numbers are so close, I feel I will be fine. Again....I understand there are seamanship and weather variables.

Thanks.....go!

Ratios can be used to compare one boat against others and I would not buy a boat without doing so...it tells you where the boat stands against the competition. You will note that cabin layout (which sells the majority of boats these days), is not included in the ratios. The established ratios have been created by knowledgeable designers/sailors to get a glimpse of how a boat will perform comparatively; that's more objective than reading a magazine review. If you put a number of boats on a spreadsheet (I have about 4,000) and sort for specific ratios boats will congregate into typical categories: racer, bluewater, coastal, cruiser, etc. That is not to say that one cannot function successfully outside of its designed purpose...it just wasn't designed with that particular quest in mind.

Good luck on your voyage.

~ ~ _/) ~ ~ MJH

[GordMay]

Originally Posted by barnakiel

To me, comfort ratio is pure BS.
Maybe the guy who invented the metrics had interest in which boats pop up as comfortable? Maybe he was a boat designer? Murky waters, useless ratios ...

Quoting the “guy”* who dreamed up “Motion Comfort Ratio”:
“COMFORT RATIO (CR):
This is a ratio that I dreamed up, tongue-in-cheek, as a measure of motion comfort but it has been widely accepted and, indeed, does provide a reasonable comparison between yachts of similar type. It is based on the fact that the faster the motion the more upsetting it is to the average person ...”
More ➥ https://www.tedbrewer.com/yachtdesign.html

*Ted Brewer ➥ https://sailboatdata.com/designer/brewer-edward-s

[s/v Moondancer]

Sailing to the Bahamas from South Florida is coastal cruising, directly from Nova Scotia is not! All a matter of being sensible.

[cal40john]

Some have argued that the Capsize Screening formula is too simple and does not give meaningful results. This Ocean Navigator article says that it is probably useful for boats of a similar type, but it has weaknesses. Here is a paragraph on the weakness between dissimilar boats from -
Assessing Stablity - Ocean Navigator - January/February 2003
It should be noted, however, that since the capsize screening value is a function of displacement and beam, any two boats with the same displacement and beam will have the same capsize screening value. This is so even if, for example, one boat has a heavily ballasted, deep-fin keel, while the other has a centerboard and internal ballast, in which case the former will in fact be much more stable.

[Don C L]

Originally Posted by cal40john

Some have argued that the Capsize Screening formula is too simple and does not give meaningful results. This Ocean Navigator article says that it is probably useful for boats of a similar type, but it has weaknesses. Here is a paragraph on the weakness between dissimilar boats from -
Assessing Stablity - Ocean Navigator - January/February 2003
It should be noted, however, that since the capsize screening value is a function of displacement and beam, any two boats with the same displacement and beam will have the same capsize screening value. This is so even if, for example, one boat has a heavily ballasted, deep-fin keel, while the other has a centerboard and internal ballast, in which case the former will in fact be much more stable.

My $.02 is that I agree with John. First, I think the Pearson 33 is a good boat and probably just fine for what you plan, as long as YOU are comfortable with its motion. More importantly to me is the Gz curve for your boat and my own preference is to see as much in the positive as possible. I haven't found the Gz curve for your boat, I am looking, but here is a blurb on it that might be helpful, though you probably know it already:

https://www.sailboat-cruising.com/gz-curves.html

[glcalahan]

Don C L

Thank you. I was really at a loss over the Gz....I have no idea what that is!

Re my acceptance of a rough ride?? I already had that with my ex. Now, that was rough..... [emoji3]!!!

We all know that **** changes quickly out there. You have to ' go with the flow'. At 69, I will soon to find out!! Next spring will be an adventure!

Thanks for the responses!!

GC

[Don C L]

I kinda wonder about that "coastal cruiser" thing too, like it's less of a boat (?) I've seen many conditions perty darn near to a coast that were perty raucous!
May you have 15 kts on the beam and 1-2' swells wherever you go!