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brokesailor 04-13-2012 03:35 PM

Crealock 37
What does it mean when they say the PSC 37 lacks reserve bouyancy aft? What determines it?

MarcHall 04-13-2012 04:53 PM

Re: Crealock 37
The canoe stern provides limited volume. The lack of volume translate into a lack of bouyancy when compared to other boats with more truncated sterns.

When you add weight to the stern, the actual waterline climbs above the design waterline and the boat "squats" into the water.

The boat has lots of storage in the rear 1/4 of the boat. Quarter berth serving as a garage, the cockpit lockers and the propane locker. In cruising mode these can end up being filled with a lot of heavy gear.

Marc Hall
Crazy Fish, Crealock 37, Hull 207

SVArgo 04-18-2012 01:14 PM

Re: Crealock 37
I would counter by saying who says the PSC 37 lacks reserve buoyancy, and lacks reserve buoyancy compared to what?

Reserve buoyancy is defined as the buoyancy provided above the intact waterplane of the vessel.

So, any discussion of reserve buoyancy really has to take into consideration the design of the hullform as a whole. Crealock designed the 37 as a double-ender (aka canoe stern or cruiser stern) and in order to bring the stern back to a point requires reducing the beam as you move aft. A typical modern cruiser with a reverse transom (Beneteau, etc.) has the cutaway transom with boarding area, etc., so more of the full beam can be carried back aft, providing volume, etc.

That said, much of the cutaway on the reverse transom type hullforms can entrain alot of water, and while water can in theory enter the drain hole on the PSC propane locker, I would still consider this intact buoyancy. So, based on the overall buoyancy and potential loading curves of a PCS 37 and reverse transom, I'd say that the PCS actually has as much or more reserve buoyancy. Particularly considering that the distribution of that buoyancy on a reverse transom hullform is much further forward. Also, the additional loading of the weight aft results in "trim." "Squat" would occur as the vessel's stern is pulled down due to increasing speed or shallow water effects.

Then there's a whole bunch of other stuff on hullforms and transoms on seakeeping, speed, etc., but that's for another post.

Hope this helps.

Time Traveler 04-22-2012 12:25 AM

Re: Crealock 37
"water can in theory enter the drain hole on the PSC propane locker"

Just FYI: Water does enter propane locker if engine is pushing hard. During sea trial last year, with Yanmar 4JH2E at max rpm (3800), stern squatted enough to put about 6-10 inches of water into the propane locker. But since the boat seems to be already at hull speed at less than 3000, that's not a situation I'd normally expect to encounter.

s/v Annie
Crealock 37

brokesailor 04-22-2012 03:22 PM

Re: Crealock 37
That's interesting because my Crealock 37 does not have any drain holes in the propane locker. I was wondering if others did.

pc37howard 04-22-2012 03:30 PM

Re: Crealock 37
my 37 has the 2 holes in the propane locker , it helps with ventilation of the locker. also i have a intake to one side of the locker hatch .

DaveMancini 04-22-2012 06:50 PM

Re: Crealock 37
Just a comment (ours is a 34, but we have the same holes): we do not use propane so we have bunged the holes with rubber stoppers. Keeps the locker nice and dry and makes the buoyancy issue moot.

Dave Mancini
PSC34 #305 "Swan"

MC1 04-22-2012 11:07 PM

Re: Crealock 37
Brokesailor - I'm surprised to hear there may be some older Crealocks that do not have propane locker vent holes. If so, PLEASE remove any propane from the boat until you get this serious issue taken care of (I'd recommend you contact the pacific seacraft factory if you have any questions about the need to do this).

As you probably realize, it's critical for mitigating the risk of explosion in the event of any leak that propane locker vent holes exist and that they are as low as possible in the propane locker (since propane is heavier than air and any leak must be able to quickly vent overboard). It's also critical that the propane locker be air-tight sealed off from the rest of the boat and this should be tested from time to time. I'll discuss this aspect a little further in a separate thread.

BirdBrain333 06-13-2012 06:30 AM

Re: Crealock 37
Back to the reserve bouyancy aft; after watching that stern rise over some quite impressive seas during this past year it seems to me the boat may not have the reserve bouyancy of something like an Island Packet, but it has as much as it needs to ride perfectly. I LOVE watching those waves racing up at us and the boat suddenly lifting before them. Seems like magic but is really "reserve bouyancy" at work!


SV Kenlanu

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