Rounding up under pressure

Sorry have to agree with other guy ....

Momemtum is created by acceleration .... constant speed / direction is a matter that carries INERTIA.

The question of not making around the corner is a fact of inertial resistance to change of direction or speed .... NOT momemtum ..... BUT momemtum will be created with the change NOT in the run up to the change.

Anyway its off topic and does nothing to stop my boat stuffing head into wind !!!!
 
You have same problem as I ...

I have shortened forestay maximum - next i would need surgery on mid lowers etc. + extenders on back-stays ... I have moved mast as far forward on step as possible ...

I have done everything possible to move CoE forward and reduce the constant weather helm that needs anything up to 20 deg offset rudder ...

If I want to use autohelm ... I have to slack off so much - near to dumping main to get it to stay on track ... that is when pointing ... on reach all settles into a groove as the wind has a large attack angle and sails can be slack sheeted ... without losing drive ...

By the way ... what ever happened to the old sailing terms :

Pointing, Close reached, Broad Reach, Running, etc. ??? I know most are still used - but for example ... pointing ... haven't heard that for years .....
 
Interesting points ...

Now one fact that tends to get overlooked ...... with many boats having large sweeping gennys .... there is a lot of sail aft of the mast ... this in effect brings the gennys centre of effort aft ..... reducing the genny can in fact push CofE forward as the sail's clew is brought forward and the bulk of sail is further ahead ....

Now this brings us onto some interesting thoughts .....

Does a mast rolled main have a better way of miving CoE forward as it rolls up into mast ?
Does a loose footed main have better effect on this when reefing or not ?
Does a furling genny move CoE forward better than a hanked on smaller sail ?
 
Yes Olewill, I think you are pretty much on the ball there. I reduced the size of my headsail (surgically, I had a triangular piece removed from the luff) and it straight away made the boat more controlable in puffs without the constant attempts at rounding up. The remaining rounding up is when really hard pressed and I put it down to underwater dynamics, the net result being tiller under my chin and boat rounding up without my permission.

misterg; you're right in that I got fed up of typing the reply which was becoming complicated. In order to rake the mast forwards and maintain any bend the lower forward inners will need to be shortened, probably more than the riggining screws will allow, so the shrouds would need replacing with shorter ones. That's if your rig works in that way.
 
I do have this problem, to an extent, and seem to have solved it by 1. Progressively reefing so that the boat is kept to 15 degree heel or less and 2. Using a new, small, foresail (No. 2 Yankee), instead of a very old genoa. This has solved the problem but I am now considering using a new genoa to obtain more speed in lighter winds on the basis that the new genoa will pull more towards the front of the sail and hence provide better balance than the older, blown out, genoa. Grateful for any comments! Of course the new genoa would be progressively reefed as the wind increased until it has to be changed for the yankee.
 
Will, I have been wondering if remodelling the steel plate blade to a proper aerofoil section would have any impact on the problem and may well try it following your comments. It woud be quite easy to do. Increasing the depth of the blade is a non starter I'm afraid but I could extend aft a bit without causing problems. When reorganisng the sail plan this year I used a virtually new, loose footed sail of roughly the same luff dim as before but a shorter foot. The bigger jib is a a jib not a genoa and does not overlap the main so does move the combined CE for'ard. Any bigger and it would overlap.

'Scruffy' sails best when fairly flat so I tend to trim to keep her within 5 to 15 degrees. This also keeps her rudder blade in with a chance of holding.

This whole thread is throwing up some interesting stuff not least the confirmation that there are a lot of boats out there with similar problems.

This is not a quest for speed. A boat like mine is not intended for performancesailing. I am looking for the best balance I can get within practical constraints. Once achieved I will be content.
 
Good. So we've established that there is more tension in a centre mainsheet than an aft one.

So it doesn't matter where you put the sheet, the tension will be inversely proportional to the distance from the gooseneck. Wherever the sheet, the sum (force x radius = turning moment) comes out the same. QED
 
Re: Interesting points ...

[ QUOTE ]
Now one fact that tends to get overlooked ...... with many boats having large sweeping gennys .... there is a lot of sail aft of the mast ... this in effect brings the gennys centre of effort aft ..... reducing the genny can in fact push CofE forward as the sail's clew is brought forward and the bulk of sail is further ahead ....

Now this brings us onto some interesting thoughts .....

Does a mast rolled main have a better way of miving CoE forward as it rolls up into mast ?
Does a loose footed main have better effect on this when reefing or not ?
Does a furling genny move CoE forward better than a hanked on smaller sail ?

[/ QUOTE ]

I'd have thought that irrespective of reefing system, the reefed mainsail is going to occupy the forward bottom corner of the mast/boom axis, so reefing system shouldn't make any difference. Except that a slab reefing will probably achieve a flatter mainsail shape, which will help reduce weather helm considerably. My Contessa can have considerable weather helm unless correctly balanced, and the first things one does when the wind gusts is flatten the mainsail.

BTW, I hadn't thought of it before, but now you mention it, I guess that another reason why hank on genoas are so much better than roller ones when the wind blows up, apart from sail shape, is that when the roller genoa has a few rolls in it the active tack of the sail rises above the deck, which raises the centre of effort of the sail higher above the waterline. That may be not a bad thing with a roll or two, but if used in a gale where there may be several rolls, apart from awful sail shape, you have this bag half way up the forestay, which must increasing heeling moment for a given wind speed?
 
rolled part genny .... well even before that !!

<<BTW, I hadn't thought of it before, but now you mention it, I guess that another reason why hank on genoas are so much better than roller ones when the wind blows up, apart from sail shape, is that when the roller genoa has a few rolls in it the active tack of the sail rises above the deck, which raises the centre of effort of the sail higher above the waterline.>>

My genny even when full out is cut way too high .... I really do not know what previous owner was thinking about .... >>

s-anne.jpg


I have many times considered swapping it for a more deck sweeping job ... and of course as the genny is rolled away ... it literally gets to about halfway up the stay when fully rolled .....

The sheet traveller and acr is too far forward on deck and is a joke - so I often if wind etc. is certain way - have barber hauler to the sheet instead of through car block ... If I was to have a deck sweeping genny - which the car / traveller is obviously more designed for - that would improve both counts ....
 
Re: rolled part genny .... well even before that !!

Yup, my roller genny is nicely cut as these things go, but even so I've been dreaming of replacing it with a hank on sail, and acquiring a No.1 while I'm at it, which I reckon would save a lot of diesel.

As it is, when the wind pipes up instead of reefing the genny I just roll it away and set a No.4 on a removeable inner forestay. The difference in performance is amazing! I reckon it adds 2 knots to boatspeed when close hauled in a F6/7, and makes the boat track sharpish to windward instead of being blown sideways.

I'm always amazed that roller genoas are so popular. Yes I know they're easier to raise and drop, but hank ons are not that hard, and if we wanted an easy life, then staying at home in the first place is much easier still.

End of rant.
 
Re: rolled part genny .... well even before that !!

I bet he bought a genny from a fractionally rigged boat with the forestay at more of an angle. The luff looks a bit short as well. I have a headsail that's too short in the luff. Some people will make do, but it annoys me. I was offered a brand new genoa for a Bennie for £100, but when I put it on the boat it ended up with the clew flying way too high. Shame
 
Re: rolled part genny .... well even before that !!

Nigel, I am going to sound really stupid now but here goes. Isn't your boat masthead rigged and wouldn't that genoa set better if was on 3/4 or 7/8 fractional? That would drop the clew a bit at least. It looks from the pic that it is just the wrong genny for your rig.

The other thing is that roller gear will always raise the foot of the sail off the foredeck so not much to be done about that but obviously the sail could be a lot longer in the leach.

I do think she is a really nice looking boat. I'd be very happy with something like that.
 
Re: rolled part genny .... well even before that !!

Not stupid, you're probably right. I hope so anyway. I just said the same thing 14 minutes before. /forums/images/graemlins/shocked.gif
 
Re: rolled part genny .... well even before that !!

I tried it in the threaded mode (is that what it's called?) Couldn't get on with that.
 
Re: rolled part genny .... well even before that !!

Genoas with low clew and deck sweeping cut are good for going upwind but when you ease them out you cant get enough downwards force to stop them twisting off and loosing power in a broad reach, therefore the high cut sail is far more versatile for a cruiser where you can easily adjust the angle of sheeting from near vertical to quite flat, but you do need barber hauling arrangents in place.

On a racing yacht with the deck cut upwind sail you never use it in a broad reach as the kites up.

A very versatile arrangement for a nice shaped foresail is getting a reefing genoa, ask the sail maker to put a couple of slab reefing points, it lowers the centre of effort and maintains a good shape, you just tie up the foot of the sail, and clip the tack to the next hole.
 
Re: rolled part genny .... well even before that !!

Two Pennyworth Time

I'm coming in late on this one and I have tried to read all the posts and I'm sorry if I am repeating something that has already been said but, here are a couple of points

15 degrees on the helm - this should be no more than 5 under normal conditions. which leads me to the second.

If you want the cheapest, quickest way to move the CoE forward - use the halyard tension . Where do you set the max draft on your sails? and does this move in the gusts ? If so check that your halyards lines are pre-streched.
 
Re: rolled part genny .... well even before that !!

Halyards are prestretch and with the main I am playing with this year I have adjustable outhaul and cunningham, both of which do help. The cunninham in particular has been a boon and something I got used to in dinghies. There's bit too much resistance in the luff groove/sheaves so will be sorting that this winter with the mast down. This is not helpful when tensioning the luff so is one to sort with a good clean and lube.
 
Luff ... I know - but stupid iriot - original owner that is ....

The groove foil stops and that luff fits it to max ... if you save and then zoom the photo ... you'll see the halyard chuck and top of foil ... with luff right up. Its been that way since boat was built in 75 ....

When I bought it - guy who was a Sail Training Assoc skipper ... reckoned first owner got the mast from another boat and sails as is ... he then proceeded to motor everywhere ...

Well I couldn't believe it when unfurling the genny - furling line was 3ft too short ... had to rig a completely new line ...

Huh Hmmmmmmm
 
Re: rolled part genny .... now look at this ....

I think the idea was as she is basically a heavy motor sailer .... that he wanted to a) see where he was going, that explains the cut away foot, b) set the furling gear foil length as per what he bought ... possibly secondhand ... so luff is that finish.

When you look at the sale sheet for the boat .... >>

sunrider25.jpg


You see a completely different set-up .....

And look - she has a flipping race number on her !! Now that is optimistic ..... (on the aft 1/4 rail ....)
 
You must log in or register to reply here.

Share this page

Top