Nondouble bottom boats

[gerry ledger]

Having discused over a bottle of wine or two at NORFOLK WEEK and burton week that there is a case for nondouble bottom boats because some of us are not as agile as we were but still like to sail 12s and find scrabbling around in a double bottom boat uncomfortable. I think there are sailors out there that would like a new boat and have no intention of doing champs but would like a modern design.All we need is a builder (not me) so what do we think?

[davidg (Guest)]

Hi Gerry,

I have wondered whether the following mods. might make for a more easily sailed boat?

Raising the sheer slightly, therefore having the deck higher relative to the double floor (same height difference as AC boats),

Having some kind of side benches, which could also stiffen the boat up,

Lowering the double floor so the boat is only partially self draining, like RS200, or a two height double bottom, like old Hornets or FD's.

The benefits of the double floor are that they stiffen the boat up, you do away with self bailers and you don't have to sail the boat in a way that keeps the water out.  

Your boats with the back tanks went some way down this route since you could survive a leg with a fair amount of water in the bottom, it would be interesting to see if a big back tank and a front tank that came back to the shroud base, would make an easier boat to sail, whilst being as stiff as the DB boats.  You would still need self bailers though.

Is it the height of the double floor that is the problem or the fact that the new boats are also so beamy?

Regards,

David
N3461

[RogerBrisley]

Gerry,

Is there anything in the rules which prevent a boat from having a longer mast,  raising the boom to allow easier passage across the boat?

I have a design 8 and with max kicker on get some dodgy moments when the boom crosses the centre line and catcches my B aid.

Lifting the boom seems to me to be a simple answer,  and not much lift would be required so may not be difficult to do?

Roger
3334

[Jimbo41]

After having been filled with water after a capsize yesterday in my Tigress, I couldn't get the water out and kept heading into wind. We ended up drifting into shore and walking her around to a suitable point to bale. Disaster is in my opinion programmed into AC boats without enough uplift to get the water out and with a heavy crew. I personally am on the lookout for a reasonably-priced DB Chapter, since in Autumn the gales throw us around too much on the Ammersee.

In answer to Davidg's posting, the bouncer(I think) was once also designed to have tanks all around. It looked like a mens' urinal, but wasn't self-draining. You still required Andersons in the floor. The result was also a bit tight for getting around, but at least you could stretch your legs. Good for all those with dodgy knees.

Another alternative would be to carve out a DB and leave enough bouyancy in the boat, fitting Andersons in the bottom. Seems a bit of a waste, but there you are.

Cheers

Jim N3130 (Don't accept sweeties from a plastic fantastic   )

[Jerry G]

Have some of you been listening to my musings on a customised "geriatric" twelve?  I had been thinking of increasing the hull depth on a standard design of hull to give scope for a thwart (essential for geriatric crew) sufficiently high above floor to help crew's knees.  Also helping geriatric helm stagger from side to side when tacking or gybing without tripping over the gunwhale when he gets there!  Extra windage from high freeboard does not seem to harm Gavin's boat.  Boom height would also have to increase at least as much as the extra sheerline height.  A plus point would be the raised sheerline would give scope for increased beam forward and aft without severe distortion of hull shape.  Downside is extra freeboard can make recovery from capsize more difficult.

Designers please note: if both helm and crew are geriatric then hull must be a weight carrier!

[Terry (Guest)]

Gerry

I think Gavin Willis has all your answers!

Terry

[Paul Turner N2487/3500 (Guest)]

Very interesting discussion here coz, as many of you know, I have to sell Crazy Diamond because my knees will not cope with the clearance between floor and boom ie deep squats or crawling/falling on the knees.

1. The coven who crew for me say that they will all mutiny if I get a Gavin boat; the Old Dragon has also threatened divorce!

2. I can get the water out of the China Doll which only has a bow tank and two rear bouyancy bags but it does take some time; there must be a way to increase the lift without partial double floors (which add weight as well as strength). The bouyancy bags are useful protection when the helm falls over! What about small bags each side of the centreboard case positioned so as not to trip up the crew? More self balers?

3. Dolly Daydream has a high boom end which lifts the cross measurements and makes tacking much easier.

[Tim L (Guest)]

[gerry ledger]

A few answers,
Roger, mast hight isgoverned by a measurment from the sheerline but there is nothing to stop you raising the boom but that means new sails to fit.
As for Jimbo if there is enough wind to capsize there is enough to empty it, unless it is gusty. Sit well back plate at least half up to bearawy onto a reach
David I have built boats with the front tank back to the plate case and same hight, a wide  plate case as bouyancy and low stern tank ie a db with a foot well, it worked well

[Alex D]

Interesting stuff... I have a wide AC with a double rear tank about 18" deep with an open transom. There is a step of about 5" into the foot well and self bailers. Lots of room under the boom.
I still getting the hang of it and we have been swimming more often than not in the recent gusty weather.
The advice given  by Tim would seem to fit the bill and I will try getting further back, rasing the plate and putting the power on. My main problem at present is with rescue crews who think we must have a problem as we sit so low in the water when filled and are really keen to rescue us.

Has anyone tried to build a duct/pipe with a non return valve throught the rear tanks from the floor well to speed up the draining once underway again?

[tedcordall]

I don't know about 12s, but a chap who works for us has a races leaders and they have 2 four inch waste pipes through the rear tank with a crude rubber flap as a non return valve. Apparently they work quite effectively. (Of course in a 12 they would have to be carbon tudes with mylar flaps )

[John Murrell (Guest)]

One solution is to put draining tubes through the back tank and then use plastic funnels to seal the holes. A bit of bungee knotted off will keep them under tension. Very low tech stuff - we used to do it back in the 70's and 80's! It worked very well on my Mr Jones

[Philip David (Guest)]

Further to Tim's comments, I would stress the need for the crew to back the jib as soon as both people are in the boat to ensure the wind is gets onto one side - the boat always seems naturally to start off head to wind and in irons. The helm usually has first to unwind the mainsheet from the tiller. Once moving, sit far enough back to stop water coming over the bows or the whole object is defeated.

Regarding the rear tank - a lot of boats built in the eighties had these low rear tanks. I have never really had a problem with them restricting the flow of water. Once the water level is below the tank top the self-bailers do the rest. I certainly would NOT consider fitting tubes through the tank as these would always be a leakage problem. The only advantage I see in bags is that leakage is obvious, i.e. they go flat. The rear tank adds greatly to the stiffness, which is one reason (I suspect) they were popular at the time.

Finally, I have always struggled getting the water out on a river as I always seem to capsize when it is gusty - and then it goes flat calm again.

Philip, N3217 (baggy with tank) & N2545 (doll with bags)

[Jimbo41]

TimL and Gerry,

Thanks for the comforting propaganda. One question. What happens when there is so much water in the boat that it keeps on coming in over the deck towards the transom (model Tigress Bob Hoare, aka Midnight Blues) ? Is there a remedy for this kind of ailment (appart from of coarse either rapid weight loss or jumping out for a  whilst the crew does the bailing housework)? I've tried increasing the bouyancy bags at the rear, but that just leaves less room and is something (more) to trip over.

Jim N3130 (give me your...etc and forget the sweeties..)

[Tim L (Guest)]

No that's prefectly normal Jim - what you're trying to achieve is enough acceleration that the boat will suddenly empty i even if water is at first coming across the aft sidedecks.  Fitting bigger bags aft actually defeats the object as you want to keep the boat at as steep a 'bow up' attitude as possible.