Pilot Houses and Heavy Weather

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tmh900

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I remember reading in Heavy Weather Sailing that boats with more sturcture above the deck (e.g. pilot houses) had less inverted stability - i.e. greater ability to right themselves when inverted. Always struck me as a bit odd, but must be correct.

I saw a review of a new boat recently that had an all positive GZ curve, but a lot of 'glass' in the pilot house. Seemed kind of strange to me that conditions that could capsise a boat would just as likely to break the 'glass' and the boat will sink. Or...is there a bit more to it than that?

P.S. the boat review concerned was the Haber 800C4 reviewed in PBO, which is Cat B, but a Cat A variant is planned.
 
Yes it makes sense, provided the pilot house stays empty of water, which implies well sealed and strong doors on it.
Open 60's tend to have raised decks now for this reason.

The GZ curve tells you about stability in flat water. Most capsizes of yachts involve a broadside wave. A boat with weght high up, such as a pilot house, may have more inertia once it has started rolling, but as no two freak waves are the same, I see limited value in worrying about the detail. If you are going out in storms, you need a strong stable yacht, elegant detail in the GZ curve is no substitute for this.
 
We have a pilot house yacht and have storm boards for all the windows. Never used them but they are under a bunk in readiness.
I have seen several GZ curves for pilothouses and the Southerly yachts demonstrate the increase in stabilitythat the raised coachroof gives.An essential factor is that it should not be overweight.
The latest Moody (the one with the garden shed on deck) apparently has a stability curve which never goes negative.!

The main practical advantage of a pilot house is that you can have a cup of tea in your shirtsleeves in Heavy Weather!!
 
Look at the design of Lifeboats. They all have what appears to be huge superstructures for a good reason.

Donald
 
To be of use in improving stability the superstructure must be watertight.


Watertight superstructure:-
Lifeboat.jpg



Watertight superstructure?
3603_boat_sales_boat_detail_lightbox.JPG
 
What would concern me most is the scenario where breaking waves, not quite big enough to invert the boat, break the windows and get the better of the frighetned man with the bucket.

On some of these boats you'd need an interesting set of storm boards (and somewhere to screw them).
 
Nah, the orange one looks top-heavy to me. Get caught beam-on to a seagul's chuff and it would be over. Then they'd expect to be rescued for free. /forums/images/graemlins/grin.gif
 
[ QUOTE ]

The latest Moody (the one with the garden shed on deck) apparently has a stability curve which never goes negative.!



[/ QUOTE ]

YM test report here
 
The moody has a ballast ratio of less than 25%. I don't think Adlard Coles would approve?
Also beware of GZ curves which don't include optional extras, how many Moody 45's won't have a radar up the mast?
And is it calculated with the patio doors open?
Ask if you can measure it yourself on their demo boat!
 
That is absolutely the point. It's also true that the relative top hamper weight of a lifeboat superstructure is very low keeping the C of G well down while providing reserve bouyancy in capsize conditions. The greenhouse on the yacht won't do the same thing at all.
 
I spent 4 days and nights going to N.Spain from Plymouth last June in a boat with a pilot house and compared to my open cockpit it was in many ways a luxury.
The downside was that each day I just had to get my gear on and get outside for an hour or more, otherwise I felt a bit 'trapped', even claustrophobic inside. On the return trip I felt this even more yet the weather was so bad at night I could readily appreciate the benefits.
A bit like having a wonderful garden yet only being able to see it from inside the conservatory.
 
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