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-   -   PSC 31 Stability & Blue water questions (http://www.sailnet.com/forums/pacific-seacraft/59509-psc-31-stability-blue-water-questions.html)

seanmc8000 11-03-2009 04:08 PM

PSC 31 Stability & Blue water questions
 
Hi All.

Have been following the forum for years now. Thanks for all the helpful advice. I am very interested in buying a second hand Pacific Seacraft 31 for a circumnavigation (tropical route). I am hoping someone could help me with a few questions.

- Has anyone done any long blue water passages in one? How have they found them?

- Could it be suitable for a couple (as a live aboard)? Does anyone live aboard one?

- I can find stability data on the 34 and 37, but not the 31? Does anyone know how the 31 compares?

- To help decide which year to go for - how has the construction changed over the years? Were there particular years that PSC implement different fiberglass, strengthening or manufacturing techniques?

Thanks for any replies. Sean

teejayevans 11-03-2009 06:22 PM

- Has anyone done any long blue water passages in one? How have they found them?
I singlehand, so 2+ days has been my limit, can't help you there.

- Could it be suitable for a couple (as a live aboard)? Does anyone live aboard one?
Yes, but you don't have a lot of large storage space (except for the
q-berth), a 9' dingy will fit on deck but its tight assuming you have
cutter rig, and if going offshore, you need it.

- I can find stability data on the 34 and 37, but not the 31? Does anyone know how the 31 compares?
Capsize ratio for 31 is 1.77 vs 1.68 for the 34.

- To help decide which year to go for - how has the construction changed over the years? Were there particular years that PSC implement different fiberglass, strengthening or manufacturing techniques?
Around 1990 they started using vinylester on the bottoms for blister protection. I think they use to use cables in the steering before going
to fix rod, no idea when. Every year they seem to make minor changes
here and there, but basic construction has been same.

Tom

Jeff_H 11-03-2009 06:38 PM

"- I can find stability data on the 34 and 37, but not the 31? Does anyone know how the 31 compares?
Capsize ratio for 31 is 1.77 vs 1.68 for the 34."


But of course the capsize ratio carries not a bit of useful information about stability or how likely the boat is to actually capsize which is the heart of the question.

JohnRPollard 11-03-2009 06:44 PM

The designer's calculated Limit of Positive Stability (LPS, aka AVS) for the boat is 139 degrees. The 34 has a calculated LPS of 144.

MC1 11-03-2009 07:48 PM

Jeff - I presume you mean that dynamic stability (boat in motion, seas in motion) may be quite different from static stability (boat at rest, seas still - how far can you tip it over and have it still pop back up), and you may be alluding to the studies that show that regardless of the stability ratings, basically the larger / longer the boat, the less it is likely to capsize . . . yes? Probably this question been discussed ad nausea in other threads, so we can search for them.

Even so, perhaps the numbers may still be of use as a means of comparing the likely stability of very similar boats to each other?

Paul_L 11-03-2009 09:43 PM

Look what goes into the capsize screening formula, i.e. Capsize Ratio:
Capsize Screening Formula = Beam / (Displacement / 64)1/3
Displacement is in Pounds
Beam is measured in Feet


It really doesn't tell you much of anything about stability. Like the weight can be anywhere and not effect stability -- I don't think so.


Paul L

SVArgo 11-03-2009 11:46 PM

Quote:

Originally Posted by Paul_L (Post 538244)
Look what goes into the capsize screening formula, i.e. Capsize Ratio:
Capsize Screening Formula = Beam / (Displacement / 64)1/3
Displacement is in Pounds
Beam is measured in Feet


It really doesn't tell you much of anything about stability. Like the weight can be anywhere and not effect stability -- I don't think so.


Paul L

The denominator in that equation is the cube root of the volume. (64 is the specific gravity of seawater, so that is just giving you the immersed volume), so it's really just a simple ratio of beam to volume.

It's one of those things you use early in a design to see if you're in the ballpark, but Paul and Jeff are right that it doesn't really tell you heaps about the real performance of the hull.

There's a reasonable chance that PacSea has the righting arm numbers and be willing to share, or at least tell you what the heeling angle at least positive stability is. I know there are also some really excellent PacSea brokers out there who are encyclopedic with this stuff.

lsbrodsky 11-05-2009 08:32 AM

Back to the less numeric questions, I sailed mine for over 15 years. My longest bluewater period was about 4 days and it was a pleasure. On shorter passages, I had the boat under sail in every imagineable condition from light air to 50 knots of wind gusting to 60. I survived all of it just fine. Having said that, the boat was at its finest in about 15 knots of wind with maybe 15 degrees of heel.
Two people can live aboard, but wife opted out of that lifestyle. I will agree that storage is small for that. I really consider the 31 a superb coastal cruiser, but short on storage, fuel and water for extended cruising.
I thought that PSC wnt to a completely different pedestal and rack and pinion steering on the 31 sometime after 2000. I don't know the year but I remember talking with the factory sometime in that timeframe and they were willing to send me the parts to convert(fee of course). I decided it was too big of a project. That was the only major upgrade in the post 1990 era that I remember. However, about the same time bronze hardware was no longer standard and for my 2 cents, bronze hardware is one of the great differentiators from other production boats.
Any used boat will have some trade-offs so your budget and the condition of the boat should really determine the decision.
Larry

seanmc8000 11-09-2009 09:19 AM

Thanks
 
Hi... Just wanted to say thanks for all the responses... Am off to look at a PSC for sale next weekend. :)


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