Nondouble bottom boats

[John Meadowcroft]

The key thing is that once you decide to get going you really go for it.  It is not gently, gently.  Pump the mainsail hard and bear off onto a broad reach.  lots of water should go pretty quickly.  once you have have got a good quantity out tack round as quickly as possible and burn off in the other direction.  after a minute you should be able to start going upwind and use the self bailers to empty.

With elvstrom bailers, the larger 'super-suck' ones are the best to have.  I consider the smaller ones a waste of time.

If you have not drained enough you will start taking more water on over the bow.  2 options sit further back or sail offwind again to empty more.  In the good old days if it was really wavy helm and crew did not go to far forward after the leeward mark in order to keep the boat dry upwind.  i certainly remember crew hiking with a leg behind the thwart.

DB boats are harder as you have no time to sort yourself out.  you must start sailing as soon as you are back in the boat or you will flip.  that said there is nothing to drain if you get it right.

from 1988 - 1998 i had a lot of practice doing this.....

john

[gerry ledger]

I started this to sound out the less agile of us who find dbs uncomfortable not those who insist on filling their boats with water as they will be better off with a db.

[Jimbo42]

[referee (Guest)]

Ok, knock it off both of you.

Discussion forums going off topic is much like death and taxes - absolutely guaranteed so no need to get miffed if the inevitable happens.....

If you want to really assess how many people are interested in single bottom new builds or variations on that theme then maybe picking up the phone to likely suspects is a better bet.

[davidg (Guest)]

Hi Jimbo,

Gerry is a gentleman and has contributed a huge amount to our class, especially in building competitive boats at a reasonable price at a time when 12's looked like furniture and were priced accordingly.

Both threads are important, Gery has highlighted an issue that may make our boats less attractive to stalwarts and newcomers, it is very easy for us with carbon double floor boats to make decisions based on our own preferences and skills that have been honed over too many years, whilst making the boats too difficult for newcomers or those with crumbly knees.  

I watched Josie and a friend sail at Salcombe Town Regatta and am firmly of the opinion that they would have found (ironically) an old Gerry Crusader much easier to sail than my DB, I would go further and say my DB has probably put them off sailing a 12 where a competitive more easily sailed 12 (single bottom) might not.

Jimbos point and the stuff about emptying AC boats is equally valid, but it would have been better to start a separate thread.  Also don't forget that it is sometimes faster to empty the boat on a beach than try and self drain in marginal conditions.

Mr Webmaster is there a way that we can archive threads that would be useful references for those seeking advice, such as righting capsizes, setting up dangly poles and emptying ac boats?

Regards,

David
N3461

[Jimbo41]

To Gerry, my apologies. Maybe I read a little TOO much Shakespear into your one-liner.

I remember talking to you at the bar one evening (Wednesday?) at BW on just this subject. There must be someone out there interested in (re) building a single-bottom that is competitive and that suits the needs of those who might, for what ever the reason, prefer a little more leg room.  

To davidg, good idea about  the thread compilation. Hopefully Josie & Co are not altogether put off by the DB boats.

To the others, thanks for your input. I'll print out and read carefully.

Cheers

Jim N3130

[martin 1262]

Watching this thread and read with some confusion?!!    ??)

Given comments made over the last month about attracting new blood into the class, i am sure we need to make it attractive for ALL people to sail, and it seems that the easier it is for older people, (and I probably would include myself there!) to sail the class, the more people there would be sailing the class from all age ranges.

Knowing how good Bim's (and others) designs are, what is stopping a builder building a Feeling foolish or Big issue in single bottomed format.. Am I missing something, or do the rules prevent that..


Am i barking up the wrong tree??

[John Meadowcroft]

Martin you are barking up the right tree.

The original Feeling Foolish is 'single' bottomed, although I believe that it is the only one that is, although Bob Murrell has done a retro conversion job on 3435 to make her 'semi single' bottomed.  The Big Issue came along after double bottoms and they are all built that way.

The difference is that until 1996 there were loads of buoyancy restrictions that builders/designers faced.  These were then removed almost entirely.  Thus the 3435 arrangement was not legal pre 1996, but does have more depth, in this case for the crew but not the helm.

The best thing about the 12 is that you can have what you what.  The issue is building a lightweight and stiff hull.  Double bottomed construction has enabled lighter hulls to be built more stiffly.  However I am sure that a full 'draining' boat is not required to get either the light hull or the requisite stiffness.

You also have great options with respect to sail plan as Gavin Willis has demonstrated.  The height of the top of the sail is restricted, but the boom can be absolutely anywhere on the mast and the relative size of main and jib and where you put the mast is entirely free.  Evidently there are some pretty familiar ratios/measurements that the majority of the fleet go with, but there is great opportunity to ignore these and go your own way as Gavin has demonstrated.

Go on, do it!

[JimC (Guest)]

How deep are your false floors? A boat will self drain with a suprisingly low false floor - my last Cherub had only a couple of inches depth at the transom. I would think if you went for a double bottom boat with a minimalist false floor there wouldn't be that much difference between that and a single floor boat,  especially at the blunt end. The only drawback with a very shallow floor is that you can end up with a boat that doesn't self drain with bow down/heeled light airs trim, but to save the knees that's probably livable with...

[JimC (Guest)]

How deep are your false floors? A boat will self drain with a suprisingly low false floor - my last Cherub had only a couple of inches depth at the transom. I would think if you went for a double bottom boat with a minimalist false floor there wouldn't be that much difference between that and a single floor boat,  especially at the blunt end. The only drawback with a very shallow floor is that you can end up with a boat that doesn't self drain with bow down/heeled light airs trim, but to save the knees that's probably livable with...

[davidg (Guest)]

Jim,

Most of the double floors are as low as you can get, I think that ours is about 1/2" above transom edge at the centreline.  The issue is a lot about the changing geometry of the boats, not only have double floors been introduced, but decks are narrower (as a result of it not mattering if water comes in) and the maximum beam is run to the transom.  Also some boats have gone without a thwart.

Meds is right, you could bring the forward tank a lot further aft than the pre-rule change boats and a stern tank and possibly bouyancy around the centreboard case would reduce the volume of water carried around (if it gets in) considerably (Soap Dish is a case in point).

The original Big Issue had a low floor (below DWL?) and a self bailer as does the RS200 and the Laser.

Personally I can live with the double floor, but if I were to have another boat I would look more carefully at the ergonomics, and I am sure I would have slightly higher topsides and probably some kind of side bench.  I hate the idea of ever having self bailers again.

David
N3461

[Mikey C]

False floor height is quite limited by the amount of rocker in the boat too. the rocker you have, the higher the floor effectively has to be to get the water to flow out the back. I think this is one of the reasons the foolish is such a handfull to get upright.

Transom flaps are actually pretty sensible on db's. stop the boat capsizing on reversing, and hold the water in the boat until you are ready to go. I always go for small transom openings to help slow the initial draining process until you underway.

As for a new AC boat, if someone wants one I will build one, but no-one has asked!

[Guest (Guest)]

I sail, and have frequently capsized the first Big Issue.
As pointed out earlier the double floor is fairly low with a single self bailer at the back, I think the shearline is also a little higher than most, although nothing like Gavins!
Following a capsize with 21 stone in the boat a poot of water about 6" deep sits in the back of the boat, this drains very quickly as soon as you get back on the move. Aside from the drag of a self bailer this seems a pretty good compromise.

Tony
N3428

[Kevin]

I think the last few posts of this topic are spot on the important points for consideration and my thoughts are these:

Stiffness depends partly on how the hull is built and what it is built from from. For instance of my two boats 3373 is built to the old rules but even today  is considerably stiffer and more bump resistant than 3491. 3373 has kevlar as well as carbon in the lay up which I believe may partially account for this. She also has a floor (single bottom) about an inch thick. Even though she has wooden decks, thwart and centreboard case capping she still carries about 10kg of correctors.

Side decks, in my humble opinion, are generally too narrow today. As well as allowing more water into the boat when roll tacking this makes them less comfortable for sitting out on in a breeze, which in turn makes it harder to sit out for long periods. 3373 is easily the most comfortable N12 I have ever sailed and when we commissioned 3491 Jane & I had Mike copy the decks from 3373. I have to say he did a pretty decent job of that so 3491 is the next most comfortable 12 I have sailed.

Draining water from the boat underway seems to be about the same whether in a single or double bottom. In a breeze it goes out the back or down the bailers at about the same rate. In light weather it sits at the front until the crew weight is moved back or it is bailed by hand as applicable. I do not subscribe to the idea that self bailers add meaningful drag, in fact when they suck air there is a longstanding argument that they reduce drag. The only difference is in a capsize when the self draining attributes of a double bottom mean that it empties far quicker. However, as plenty of people have pointed out, this can be a problem if the water goes out too quickly (i.e. before the crew is back in the boat, has everything untangled and is sailing again) since the boat can become unstable and assume the horizontal position again.

At the end of the day if the rig is kept above the hull, the underwater shape is right and the boat is well sailed it will win regardless of buoyancy arrangements. I think semi-self draining (like the original Big Issue or RS200) is right and have said so for a long time. (Could this be a significant factor in why the RS200 has outsold the 12 recently? Oops, that's another topic).

Kevin
N3491 - for sale

[philipcosson]

I am coming up to the 1 year aniversary of owning my AC 12 (baggy). Sailing it since March - I've had plenty of opportunty to right it from a capsize.

I have found that in certain conditions It really is difficult to get the full boat out of irons. I had one really miserable experience a month or so ago when i capsized on the first tack after my best ever start! I was still in irons when the lead boat came round the start line again!! (I would like to think that my slim centreboard section  also makes the boat more prone to stalling in the tack, whch could make this problem worse as well)

The advice I did get from the northern hoard was to a) keep the boat as flat as possible once righted, not heel at all and b) sheet in the jib only to get going, only sheeting the main when you have started to move.

I have not capsized since then so have not had the chance to put these tips into practice, but they sound like the missing information - cos I thought I was doing everything else that had been advised at the time.

Philip
N3253