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Old 08-08-2012, 06:57   #61
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Re: 2012 Round The Island Race (& Gemini capsize)

Sandcrab, the BOA/LOA ratio is indeed a significant factor in resistance to capsize, but it is hardly the only one. Just as with monohulls, increased displacement also increases resistance to capsize (one of the reasons that very large cats oftern have BOA/LOA ratios lower than the Gemini). Here again, the Gemini suffers due to its relatively low displacement. Cg (center of gravity) is also significant and, due to the relatively low bridgedeck clearance, the Gemini comes off fairly well in that regard. With respect to Ce (center of effort) of the sailplan, however, the Gemini comes off worse than some of the eariler British cats with similar BOA/LOA ratios: they had smaller relative sail areas and, in the case of the Prouts (with a cutter rig), sail area was distributed on more of a fore/aft basis, allowing for a shorter mast and a lower Ce for the sailplan.

Windage is also important (think of a van in a crosswind) and here the Gemini also comes off rather poorly for such a short boat: the effort to have full headroom at the companionway (and in some cases, a cockpit enclosure) in a boat that was originally 30 feet leads to a relatively large amount of windage for a boat of its size. Furthrmore, once a hull lifts, a solid foredeck allows wind/waves to operate on a larger area underneath the boat and thereby increase the forces contributing to a capsize. Finally, the boards on the Gemini are relatively large and, while this contributes to good windward performance, if the leeward board is down there seems to be an increased risk of 'tripping' over it.

Brad
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Old 08-08-2012, 07:21   #62
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Re: 2012 Round The Island Race (& Gemini capsize)

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Originally Posted by Therapy View Post
I have only sailed in Florida and St. Croix (and a couple of lakes in Georgia ) and have never really had to worry much about tides as we just don't have much more than a knot unless entering/leaving a river or some bays.

It must be a real challenge to work that into ..........err......work into that schedule.
Not really. Just like anything else it is what you are used to. and plusses as well as minuses - always good to have a few knots under the keel ....although of course that also balanced by sometimes having to suck up a few knots (or so!) against .

I have only been around the IOW a couple of times myself, and not in really bad weather .....but simply from looking at the chart looks like a lot of water trying to go nowhere (at the end of the English Channel there also be the Atlantic ), and that always has a potential for "challenges".

In the case of the Cat, I am sure the Skipper knew he was pushing his luck for the conditions (but that's what Racing is about -isn't it?!), knew full well that she could flip (unless all he had read was a certain Forum ) and just got his judgement a tad wrong.....exactly the same happens no matter what type of hull, it's just the specifics of the outcome that differ.
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Old 08-08-2012, 07:42   #63
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Re: 2012 Round The Island Race (& Gemini capsize)

All boats, motorized or sail, ships, what ever,

They all have points that you cant sail or drive them into in big seas,

A big ship, you dont drive them beam on in big seas, you can roll them over,
A big following sea can fill a motor boat with a low transom. Done it on the Ramp.
A sailing Mono can roll over in a beam on big sea with all sails up,
A big Cat can also be blown over sideways with all the sails up in a big sea.,

Once I figured out what my Gemini could and couldnt do, It was all safe sailing,
Both centre boards fully down and all my sails fully up, beam on, in a huge sea, I was close to going over sideways,

But lift the Lee board fully up and drop the main to 3/4, End of problem, Totally safe.

But I learned, Thats not some thing the Gemini does well and to avoid it,

As for pitch poling, Thats just not an issue, Unless your racing and everything is up and to the max,

I did find that nose on into 5 metre waves and a screaming head wind, Running on the diesel, If the waves were a bit higher,
There was a real possibility that I could have flipped it over backwards,
Thats another lesson learned,
I now know what height waves my Gem will sail or motor into. Safely.

Experience comes from making mistakes and learning from them,
Try not to sink or capsize your boat while learning to sail it,
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Old 08-08-2012, 07:47   #64
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Re: 2012 Round The Island Race (& Gemini capsize)

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Originally Posted by Therapy View Post
It must be a real challenge to work that into ..........err......work into that schedule.
No, infact it's the exact opposite, providing you don't mind setting sail at 5am in the morning. Last week we left Guernsey in the Channel Island for the trip North. We pushed against the last hour of tide until it went slack and then rode the big spring tide past Alderney and into the race. The tide was still pushing us home 20 miles out into the English channel, so it can really work in your favour.

It just needs a bit of planning with tidal atlases. 3 or 4 knots of tide makes a huge difference to the distance covered. The one downside though is wind over strong tides creates short choppy waves for 6 hours until the tide turns and you have wind with the tide.
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Old 12-08-2012, 21:58   #65
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Re: 2012 Round The Island Race (& Gemini capsize)

Hi Mr B,

If they had the screecher up in these conditions, the track would have likely ripped on the boat.

There are more that have gone over than were listed in a previous post. Add one in a lake in Texas a few years ago I think. And I think there was one in Long Island also.

The general reason in previous capsizes stated is not reefed when conditions warrented. Lack of experience was sited also. But large short period broadside wave conditions and boards down can be just, if not more dangerous IMHO.

Reef the boat, it sails great in winds and seas and most of the time the speed reefed is amazingly the same. We have been out with sails up in 32 knots, but reefed way down. I have about 5000 NM of sailing our Gemini around New England and the boat is reefed more times than I can count, and it is often due to wave direction, size and period in addition to wind speed and heal.

If there are large gusts and variation in wind/wave direction, reef the boat. Boards for going to windward are for when the wind and seas are the right conditions...

For the Gemini,if not racing, the conditions described seem more like a time to be motor sailing into port, slowly, or running off the wind and then reefed way way down with boards up.

Also, the holes that need to be sealed up are related to the steering cables. These are open 8 inches over the water line inside the rudder compartments. If you end up with the doors on the steps open, and you end up filling these lockers faster than the drain holes let the water out, then you can take water though the hole into the aft lockers. Fill these up, and you start taking water into the main hulls of the boat. There is the second set of holes which leads into the aft cabins. Again, these need to be sealed up also. Mr B, and other Gemini owners, this is a critical but simple fix.

Regards
Walt,
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Old 12-08-2012, 22:44   #66
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Re: 2012 Round The Island Race (& Gemini capsize)

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Hi Mr B,

If they had the screecher up in these conditions, the track would have likely ripped on the boat.

There are more that have gone over than were listed in a previous post. Add one in a lake in Texas a few years ago I think. And I think there was one in Long Island also.

The general reason in previous capsizes stated is not reefed when conditions warrented. Lack of experience was sited also. But large short period broadside wave conditions and boards down can be just, if not more dangerous IMHO.

Reef the boat, it sails great in winds and seas and most of the time the speed reefed is amazingly the same. We have been out with sails up in 32 knots, but reefed way down. I have about 5000 NM of sailing our Gemini around New England and the boat is reefed more times than I can count, and it is often due to wave direction, size and period in addition to wind speed and heal.

If there are large gusts and variation in wind/wave direction, reef the boat. Boards for going to windward are for when the wind and seas are the right conditions...

For the Gemini,if not racing, the conditions described seem more like a time to be motor sailing into port, slowly, or running off the wind and then reefed way way down with boards up.

Also, the holes that need to be sealed up are related to the steering cables. These are open 8 inches over the water line inside the rudder compartments. If you end up with the doors on the steps open, and you end up filling these lockers faster than the drain holes let the water out, then you can take water though the hole into the aft lockers. Fill these up, and you start taking water into the main hulls of the boat. There is the second set of holes which leads into the aft cabins. Again, these need to be sealed up also. Mr B, and other Gemini owners, this is a critical but simple fix.

Regards
Walt,
I found out about those holes when my steering cables crapped out the day before I got washed up on the beach, The reason I was parked near the beach, Hiding from a storm with winds in excess of 35 knots and increasing, With Dodgy steering, I was not going to sail through that storm for a minimum of 4 hours to get to Port Stephens and safety,
Port Stephens got wrecked in that storm,

They also run through the aft lockers which are not drained, you have to physically empty them out with a bucket,

If your aft lockers leak or are not sealed properly, the water gets in there and runs into the hulls, it also comes in from the rudder lockers into the aft locker and then into the hulls,

Like you said, its an easy fix, but if you dont know, its some thing you cant see easily, and if your hulls are filling with water, You would be hard pressed to find where the water was coming from.

If your in the cockpit, Your boat could be full of water before you noticed it,


I did find that if I sailed with only the Genoa up, no matter what the wind speed was, I had no problems, Very safe, 1/4 - 1/2 Genoa, no Main, and only the windward board down fully, kept it in a reasonably straight line, much easier on the Auto pilot as well,

With both boards full up, The Gem has a tendency to flick sideways to fully beam on, That can be very scary, especially in huge waves,

I have a video on youtube, Crossing the Tasman Sea in a Gemini, Day 7.
It was beam on as far as I would go, I cant sail for ****, and I certainly wasnt going to push my luck, There is a limit to how far I will push my boat, Safety for me comes first, I leave the heroics for other people,
They were pretty decent sized waves, some thing you dont get in a protected water way,

The Gemini is a magnificent, cheap and safe boat, But there are things you just dont do in them,

All boats have limitations, you just need to be aware of what they are,

Safe sailing to all,

Cheers,
Brian.
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Old 13-08-2012, 13:33   #67
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Re: 2012 Round The Island Race (& Gemini capsize)

I found on my Prout that there were only small weirs between the various compartments.
Most were disguised beneath bulkheads, all carried oily engine sump catch volume beneath the centre nacelle after heavy rain (English Summer) which rotted the floor of the area.
Do, all of you, work out ahich areas need to be isolated, which can drain to a common sump. Personally through hulls in the bulkheads seems the best idea, water tight'ish compartments can be created that way if the door is a reasonable fit and the locking bar will withstand the pressure. Water creates 1.50 pounds per square inch of area per foot of water depth. A hook and eye fastener will not keep the door (place) in place.
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