Jump to content

Smaller foresail - depowering my rig


Guest

Recommended Posts

Go to sail brokers. They have a few options. Our club website has a link to them go to http://www.weiti.co.nz/Links.htm and click on the Sailbrokers logo.

 

I think in cruise mode the Ant floats a good couple of inches lower in the water and because that bow area is empty I fill it up with fridge, dive tanks, and as much crap as I can stuff in there. It sails around like a minitun! But the bbq lives in the boat, cos during a race if it's a real drifter, I can light up the bbq, rustle up a couple of steaks and demoralise Knot Me and Fish who will be to leeward and behind.

Link to post
Share on other sites

All of this reminded me of something!

 

Originally I thought Spellbound was overpowered, in gusts she would really lift up and this made both me and the AP work harder.

 

After much research and talking to a number of people I found that it was excessive weight in the bow. I had two sets of chains and two anchors up there.

 

I moved one anchor and one set of chains to under the sole and above the keel and she stopped pointing up in the gusts.

 

Just a thought

 

SHANE

Link to post
Share on other sites

OK, I am going to wade in with another point here. I am tentative as others have far more experience that I do.

The Hull angle of heel is an important issue. Getting the right angle for the design that is. All parts of a boat is a part of an overall "Wing" trying to "lift" itself in the direction you are wanting to Helm it. I should say that is is the case for all points of sail bar down wind, where you are simply being pushed along. The Rudder develops around 10% of the over all lift of the boat. When you think about it, that's a lot of effort being placed on that little thing out the back. The Hull shape is also a wing in the bigger scheme of things. Depending on how the shape has been designed, you will have a slightly more efficient point in lift in regards to Heel than other angles. Whether that can be measured in seeing speed will also depend on the design. But at some point of leaning over, the Hull goes from "lifting" through the water to sliding over the water. What is happening is when in "wing" mode, the vast majority of water flow is in the Direction around the Hull. When heeled to far, that flow wants to take an easier path and that is under the Hull. Please note, I am not talking about the Keel here. Although it is part and parcel of the over all "wing", I am referring to the shape of the Hull and the part of the Hull that is in the water at optimum Heel. That is why a yacht does not have a Flat side (horizontally) but a curve and the main reason why a Hull does not travel dead straight in the water, but slightly side on. It is lifting through the water.

Link to post
Share on other sites
Thats why Km has(d) a plastic chain and plywood danforth, oh and the polystyrene outboard.

 

Thats right isn't it Knots? :D

 

2 Whitbread boats had plastic chain, the rules didn't state a material type at the time, they do now.

I may have seen the odd ply anchor but knot for a few years ;)

And the rules stated we had to have an outboard positioned where it would be if you have it going, it was. Again the rules didn't state the outboard had to go. I won that protest, in the Squaddy no less, and then they change the rules.

 

My Insurance company also change the wording of a policy when I sailed to Aussie one day and they said I wasn't covered of Trans-Ocean crossings. They were a bit disturbed when I said 'Sweet, I'm all covered then as it is the Tasman Sea, knot an ocean'. Took them 3 days to send a re-written policy after checking with MSA to find that the Tasman is indeed knot an Ocean :) It now runs out 200nm from the closest dry land.

 

I'm planning BBQ chilli prawns, hope the smell doesn't put AA off to much, I don't want him falling too far behind ;) It's looking lite, bugger as I think that bastard red boat likes that more than me. Where's me buckets and dive gear :)

 

I do like my little loopholes :thumbup: And despise the comment 'Oh but the intent was...'. If that was the intent why didn't you write that.

 

About 35mm difference in waterline between full cruising and nearly full racing trim for us. I say nearly full racing as she's never been full stripped out under my watch yet. I reckon that would be good for another 10mm maybe. Suss Hotdogger and she floats about 15mm higher again, but she if fully stripped out. But we are skinny so even small weight makes quite a difference.

Link to post
Share on other sites

For what its worth, there is some good advice on here.

 

Basically the Nova was designed with the large overlapping genoa you currently have.

It needs that sail to get performance in lighter airs.I think a lot of sailing in Auckland is done in less than 15 knots and hence that big genoa will more than pay its way.

 

As the breeze increases you can get away with a number 2, similar hoist, shorter foot.

 

I think the correct solution is not so much to cut down the old sail size (as you can probably do with the power in a majority of the sailing you are likely to do) but rather to make the furled sail a lot more efficient.

The padded foam (or whatever) is the solution to that.

In the short term I'm sure you can retrofit that system to your existing sail to try to improve the furled shape.

Link to post
Share on other sites
Thats why Km has(d) a plastic chain and plywood danforth, oh and the polystyrene outboard.

 

Thats right isn't it Knots? :D

And when we see Legal Documents written in the way they are today, and we think why on earth do they use a hundred words to say a 5 word sentence, it's because of slippery buggers like KM that can squeeze through the loopholes in the documents like they are covered in grease. :wink: :lol:

Link to post
Share on other sites

I would think half the issue is the old stretchy cloth, its allways goign to bag up when partially furled no mater what you do to it or how big or small it is. of course the bigger it is the larger the percentage of your sailing will be with it partially furled.

modern laminates allow you to go with an almost full size #1 and still hold their shape when furled. we still recomend going with a #2 designed size which is normally 135-140% and raising the clew slightly for better reaching and so you dont have to adjust the car too much.

half the problem is that Dacron physically lasts so bloody long that there are many old dacron sails around that are still strong but are absolutley stretched beyond belief. once the resin finish has gone they turn into hardly more than a bed sheet and its the diagonal loads that really distort the cloth as the resin which gives it all its stability has gone.

alot of people fine serious performance and comfort increases (less heel, less weather helm) whcih new sails as old baggy sails are just the worst thing for cruising boats.

 

thats just my take on it anyway, of course its much easier for me to get new sails!

Link to post
Share on other sites

As a Nova owner who has covered a few miles in her I think I know enough to say: reef main early, keep a full hoist headsail up (chico jib fits very well) and keep her shoulder down. This maximises a very short waterline and seems to stop the stern dragging. If main full batterned play the traveller, if the luff is backed this is OK for short periods. A Nova is NOT a modern boat and was designed to heel as many 1966/7 designs seem to be.Dont expect her to point too high, instead increase VMG by footing low and (relatively) fast with the bibbest headsil you can comfortably hold. My 5 cents worth. :?

Link to post
Share on other sites

Hey Booboo, as I think you may have hit the nail on the head with the old dacron and lots of old dacron is being flown out there how about a quick run down for some of us who aren't sail cloth knowledgeable.

 

A quick overview of the cloth types and rough expected lifetimes and so on. I think many don't realise just how quick some sails can 'go off' and expect them to last a lot longer than they can do in some situations.

 

Pretty Please ;)

Link to post
Share on other sites

Good to hear the alternative view summerbreeze. The Nova has pretty slack bilges and does lean over easily. But I can get a pretty wicked weather helm on her even with a reef in the main and the traveller right down. By the time I'm nearly putting the toerail under I think she's going more sideways than forwards.

 

I fear that Booboo may be right about the baggy cloth.

Link to post
Share on other sites

Weather helm can be caused by several different things.

The Main sail being sheeted in too tight or too much sail up.

Correct mainsail shape. Try flattening it, use the vang to maintain the shape and then ease the sheet.

Heeled over too much.

Too much weight in the Bow.

Have you got the mast standing with the correct angle backwards and Pre-bend??

Link to post
Share on other sites

Captain H, the comments about the main and old dacron are spot on. When I replaced my main the change to the weather helm was huge. (The auto-helm loved it too) How old and full is your main as your central issue may be due to the sum of many parts . Because she has fine ends pitching can become an issue so I work hard on keeping weight centred on the central hull area.

Link to post
Share on other sites

Here is my 2 cents worth.

 

The question about how long a sail lasts is a hard one to answer, I guess you can kind of relate it back to car tires, it depends on the amount of usage, type of usage and quality of the initial purchase.

Tires will last for a long time before they are actually to worn out to get you from A-B anymore, but your performance will be down, and they could blow out at any stage. Even when they fail a warrant they still have a year or so of use out of them before they are completely ruined.

For sails its even harder to pin point how long they will last as there as so many various fabrics available and so many different needs.

A grandprix racing sailor will replace their sails once the shape has deteriorated and they know they can go faster with a new better shaped sail, these sails usually get passed down through the ranks of club racing until they are completely in tatters which could be 5 or more years latter. Whereas a cruising sailor might expect his sail to be good for 10+ years and probably wont replace it unless its rotten and they cant get from A-B anymore without sail issues. So here you can see how the different uses really change the game plan.

 

Dacron has many advantages over laminate sails and $ per mile it is unbeatable, however the downsides are that its heavy and stretchy and wont hold its shape very well. It is composed of one woven layer of cloth that starts out looking like a bed sheet (ie lots of stretch on the diagonal) then they either impregnate or coat it in resin which holds the yarns together giving it stability on the bias (diagonal), its very similar to what happens to peal ply when using fiberglass, it starts of a very loose weave but when you take it off you will see how stiff it is- same principle. Most racing dacrons are coated which gives a firmer finish like a Y88 mainsail, cruising fabrics are impregnated, not as firm but will last longer. The firmer the fabric gets the less tear strength it has and it is susceptible to crack in places. Even after the resin has worn off completely the yarns are usually still intact as long as the UV hasn’t damaged them too much and in fact in some cases they even have more tear strength but have exceptionally poor shape holding and the draft goes right to the back as soon as there is any load (exactly the same thing with spinnaker fabric). People think that it doesn’t matter as ‘its just a cruising boat’ but in fact they are the worst, with usually shallow keels and a relatively low righting moment/overall weight factor, also usually with familys on board trying to get home after a long weekend away. All that combines into a long painfull trip pointing low and hanging onto the tiller with all your might, with high drag, high heeling force, low driving force sails.

deep sails = weather helm, heel = even more wether helm! I like to think of it as if you were getting towed or pushed from a point halfway up the mast which is where the driving force of the sail is. as soon as you heel it is wanting to round you up as it gets leverage out one side, this outweight any rig or rudder setups. Straight out heel is the biggest weather helm factor.

 

So laminate sails use a mylar film instead of resin, they are also built with the strength of the fiber running along the loads of the sail with ‘radial’ construction as opposed to cross cut like Dacron where there is no cloth orientation in the sail ( the process of making radial Dacron is both hard and expensive making the radial Dacron much more expensive and almost the same price as laminate), the mylar which is just a heavy plastic, gives great support on the boas as well as bonding the multiple layers of whatever fiber (polyester, spectra, Kevlar, carbon) together. Overtime the lamination and/or the mylar can break down and then the sail is structurally gone. The laminate will hold its shape (to a point) until the day it dies give it a much longer ‘Performance life’ than the Dacron, basically if they both deteriorate at a similar rate and the laminate has delaminated and the Dacron has gone soft, then the laminate cant be used but the Dacron might still have many more years in it before it is structurally ruined but it will be a sack and heel the boat over with very little driving force. So in theory the laminate lets you know when its time to replace the sail.

There are many options to help make the laminate last longer, a woven taffeta layer (like a light Dacron) on one or both sides helps hugely with the lifespan of the sail, also keeping them out of the UV will add years of life to the sail. Dropping it a furling jib over winter when you will not use the boat very much is the best thing you can ever do for a sail.

Link to post
Share on other sites

You're not wrong, particularly given that topics like multihull racing insurance and holding tanks have also rolled round again this week - as others have pointed out in the past, there are some gems of wisdom posted from time to time which seem to be hard to track down once a few months have elapsed.

Link to post
Share on other sites

On Mothership's job list is to build a wiki (I think that's what he called it) which will be the repository for all such wisdom. What's more Rigger has generously offered his time (he's a lazy bum just lying around the house these days) to go through all the archives and identify the good stuff.

The reason this site is so good is the people like that who inhabit it - thanks!!!!!!!!!!

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...