Sailing Experience

Multiple sails are often viewed as costly, but it all depends on your point of view.

 

It seems that the record breaking Idec has a center of effort aft of center on a close haul.

 

Hi Fanie,

Re Post 149

Para 1 - The simple answer is that it would slew the bows to weather causing lee helm.

Think of the daggerboard as the pivoting point. Force produced aft of this point would push the stern away from the wind, requiring a compensation of the rudder to maintain a straight course.

Para 2 - See Para 1. Moving from close hauled to a reach will still have the centre of effort behind the pivoting point – albeit to a lesser degree.

From what I’ve read on this forum in the last two years, the place for CE on a catamaran is as near as dammit to the centre of the craft.

Lekker bly boet!

 

Charlie!

Thanks for the points mate. How do you do it?!!

Missed your post while I was composing my reply to fellow saffa Fanie.

Your example of course, is a trimaran and using the basic logic in my previous reply, the lee hull takes the place of a daggerboard in a cat and is obviously distributed over a “longer” area – minimising the pivot effect.

Well that’s my reply and I’m sticking to it!!

Keep well, fella

 

Thanks Charmc,

Dunno if this will make any sense, looking at the picture -
The top row is what I experiende currently, and what the sail looks like.

During a close haul, the sail is full and ok
When reaching the sail is let out some, but with the effect it flies up some
When running the sail is out to the side and up

If it would be possible to 'add' the extra sail area on the sail foot and the leech like in the middle row -

During a close haul no change, the extra sail is 'tucked in'
When reaching the extra sail area can fill in the gap between the deck and enlarge the leach area also, since the sail flies upward and allows for fairly large sail areas that can be added.
When running the sail area would also benefit.

The bottom two images -

Left one is the standard sail running on a self tacking carr (red line). Centre of sail force is about in the centre of the hull. Sail is the triangular sail like a jib.

Right is the extended sail size with more of a pyramid form. The clew extends beyond the mast, and the red line is the carr's path of movement for self-tacking.

 

See? It’s happened again. I missed your brilliant cartoon

Thanks Charlie!

 

Nice joke

Just to explain again - the mast is at the rear of the boat, the REAR (AFT, BACK )

The sail extends to the front from the masthead with a cable and furling roller. There are no booms, Trev.

The clew, (loose end) is where the sail control is done from. Goes onto a MULTIHULL.

 

… and yet AGAIN!!

Fanie, I missed your reply to charmc while replying to charmc’s reply!?!

Can’t keep up with the pace here, man. The Friday night liquid refreshment doesn’t help either.

[Thinks…] Friday night liquid refreshment… get involved in threads?

Whoa! I think we have an answer there, lads.

See ya in the morning!

 

1. It is ok to have the genoa overlap the mast. The major problem is that spreaders and rigging are in the way.

2. You are obliged to keep a lookout, if you are on port you must give way to a vessel on starboard. These are the rules of the road which you must follow. In addition, ships occasionally run down small boats at sea, it is one of the dangers you must face, so it is important to keep a look out for ships. You only have a few minutes from when you can see them on the horizon untill they hit you and you die. For this reason many cruisers will have their jibs cut high so you can see underneath them.

3. Your plan to roll up the sail is not new. This is how headsails were reefed before roller furling. It works similarly to slab reefing. If you look at the mini transat boats you will see multiple attachment points along the luff and leech of the genoa and also on the spinnakers. You will not be able to furl your sail with the bottom rolled up so it is probably not such a good idea. If you want more sail area on a reach a staysail would be far simpler.



4. Trev explained how the sail will cause your boat to handle strangely if the sail force is infront of or behind the hull center. My experience shows me that it is only really important when going upwind(and reaching with monster spinnakers on long sprits). The force a sail produces is perpendicular to the sail surface, so when you are going upwind most of the sail is pulling sideways, and the balance is important. As soon as you free off a little onto a reach, you ease the sail and a significant part of the sail is pulling forward and does not have an effect on the pivot point. On any course beyond a beam reach the leech area of the sail is probably stalled because if the massive belly in the sail anyway.

5. I think you are going to have problems in strong wind. If you were to get into a storm and furl your sail so only a small amount remained, you would find that you can not sail upwind because the sail force is very far forward. This will pull the bow of your boat away from the wind, onto more of a reaching course(Lee helm). This is a very dangerous situation to be in, in big waves. The aft mast rig in brians original form had a mizzen which would be used to balance the boat, so would not suffer the same problems. Now consider that you want outboards on the transom. I personally do not like outboards because they can spend alot of time out of the water when there are large waves. Maybe you have considered this in your design, but this is my personal experience.

You should really consider adding a staysail, it might be in the correct location for good balance as a storm sail and could be used for extra area on a reach. At least buy a second hand one and try it out. Google "used sails"

Note : You have never told us what keel/skeg/rudders you are using and I am also not sure what you sailplan will really look like. So some of the assumptions I have made may be false.

Disclaimer : Im an idiot. I do not know what i am talking about. I am here for entertainment purposes and anything I say should not be trusted. If you want good information, read a book published by a suitably qualified NA and dont listen to what people on the internet have to say.

 

Gee whiz Deepsix, thanks for the encouraging words here... although I cannot immagine it being worse than our roads with taxi's on them TBH you have to have 360 deg vision here... it comes with practice and bad experiences

So if a tanker bumps into me, you recon I'll have some damages to the boat ? How much damage will they have ?

Just mocking you... I know they're bigger and heavier than trains. Not worse than taxi's though. I bet they don't follow you to shoot at you

On a slightly more se ri ous note - thanks for the advice. I've some more things to find out regarding sails, so all advice and critique appreciated.

The comments wrt being in a storm is valued, nice weather there never is a problem. I will certainly consider another smaller more centre sail for stormy conditions.

The planned sail setup is really simple, a single sail (now maybe two ) for sailing. Mast aft of the cabin and a single main sail used that looks like a jib. The storm jib could be detached from the deck so the main jib sail works as originally planned and then only connect the storm jib when less nice weather (wind) is under way. The main sail can then be furled and acts just as a stay for the mast.

I haven't decided a specific position for the daggerboards yet. I may position them foreward of the hull centre or even have two daggerboards per hull, one at the centre line and one more foreward.

 

The main sail area is about 50m^2.
How does 22m^2 sounds for the storm jib ? It would fit in quite nicely and leave a gap to check out for tankers

 

Im not really sure what size would be suitable for your boat, i would guess that 22m2 would be a usefull sail but if the sail is intended for survival conditions I might make it a little smaller. Google "Storm Trysail" and "Storm Jib" you might find something usefull. They are usually flourecent orange.

From the deck of a boat you can only see three of four miles or so, so if a tanker is doing 20kts is only takes about 10min from when he appears over the horizon until he gets to you. It can be quite surprising to suddely spot a ship near by. Also some ships may have a large blind spot directly infront, because the captain cannot see below the level of the bow, and I imagine picking up a small boat with white sails when there are breaking waves and spray around is probably quite difficult. Try and get an active radar reflector, that way they should see you from miles away.

 

Hi Deepsix,

I'll see which size similar size boats use. Orange or yellow is a good color.

It's surprizing how fast a tanker thravels eh ! I think even with the bright fluorescent sail it's not going to make much difference. What, the guy in the tanker is going to slam on brakes (or make a handbreak turn ) ? Even if he does spot you and goes over you I doubt he's going to make it aft in time to throw you the life ring, even if he is fit, and then to which part of you does he throw it to ? Even then if miraculously you're alive you're going to drown in the time the life ring takes to hit the water

 

It's not only how fast they travel, It's how long do they take to change course SAFELY (for them) and who (on their bridge) is looking anyway?

DO NOT COUNT ON EITHER, or ANY action from the tanker (or any large commercial vessel) - might is right

Keep hull (and sail) colours to ensure your personal comfort (heat & glare) and fit a modern 24mile (no point in larger) radar with anchor watch set for "wake up & check" every 10 minutes with audible alarm (or whatever you need to become alert on your watch or die).... . . . Lets take a case, on this perfect day you are exceeding expectations and doing 20 knots ! coming at you from dead ahead is a tanker , low in the water, likewise doing 20 knots. at 24 miles your radar may pick up the vessel but don't count on it. If properly set up, 10 minutes later at next scan, is 9 miles away. This is when you need to take immediate evasive action - if not sooner... Radar is just an aid. Do not count your life on it. It is an electronic machine - at least 2 reasons that it may fail to function add murpheys law & other failures then remember your eyes are the best insurance policy.

That is why yachties should organise watches - so someone is awake and KEEPING a GOOD LOOKOUT- AT ALL TIMES... You very seldom hear of small ships being hit by larger vessels - mostly "lost at sea???"

We had a foreign ship entering Brisbane a month or so ago & destroyed a commercial fishing boat in its correct place - the cargo boat was off course well away from the designated shipping channel...

 

Hello Masalai,

I have on my list of electronic equipment to be implemented a timer alarm that would buz softly for 30 seconds, if not acknowledged then a siren goes off. Give everyone the chance to crap the watch out for sleeping Third time, the watch gets disposed of overboard.

The turning of a tanker is something like 25km.

I'm just thankfull Eskom, our electricity supplier here in SA isn't into boating... they won't have lights on their vessels on for you to see

All my equipment will have double or triple backup / confirmation... which is what makes me a bit po with my fishing buddies who doesn't do a bit of research on being out on the sea... they just assume they'll pick up as we go along.