looking for a way to improve upwind sailing.

[Bart]

Hi, I am in the process of restoring a wharram tiki 30, and think it should perform better than it does now.

What kind of angle is normal for a tiki 30?

Below i added  photo's of my chart plotter and main sail.

My sails are about 6 years old, but might have seen more uv light than they should.  I am putting more and more tension on the outhoul on the gaff witch help to get a more flat sail.

This winter i also want to apply a new coat of anti fouling paint,   this is one of the jobs a bit lower on the to-do list, i had to fix other things first... i have some growth on the hulls.

the boat is not to heavy on the helm, it just wants to turn a bit to the wind. is that okay or should i trim it really neutral?

any idea's?

Thanks a lot!

Bart

[Maxim Jurgens]

Re head sail and shroud tension

On our T 30's and T 38's which have roller furled head sails we do not use halyards for the jib anymore. When hoisting the jib we bring it up with the spi halyard , go up the mast and tie the top eye of the jib straight to the top swivel of the roller furler. The swivel is tied permanently in position . Tensioning the luff we do with a crude 3: 1 down haul . reason we do this is that when you use a halyard any movement of the mast negatively affects the tension of the luff of the jib.You get "scallops" . Slight disadvantage is that you can not drop the jib in a hurry but then in many ,many years of sailing I have frankly never had a roller furler jam in such a way that I could not solve it without going up the mast . Partially reefed jibs on a furler always look horrible and perform poorly to windward. It helps a bit if you specify your  ( next new ) jib to be cut like the main : flat as a pan cake , no belly, nothing . I got this tip from a well known racing sailor many years ago and I wholeheartedly agree now.Alternatively convert to a hanked on jib with a couple of reefs in it . Or make two fore stays beside each other  , one for  a big jib and one for  a little one .

Tensioning the shrouds is easiest by simply going sailing. You need a friend to come with you to steer the boat whilst you do the tensioning  .When on the one tack you take up the slack on the leeward shrouds. You then tack and repeat the process on the other side .  You can achieve a really tight rig this way .  

Groetjes 

                                                    Maxim Jurgens

                                                       Siam Sailing, Phuket                                                        

 

[Björn]

Hi Maxim,
what helped a lot to reduce the halyard friction has been to change the rope to some very soft and smooth polyester rope. The thickness of the sail cloth is also a factor, on my Tiki rigged Pahi 31 I had a lighter mainsail and this has been dropping easier as well. Still taking the sails down offwind was always a bit of abstruggle (depending on wind strength) but in my eyes mostly because sail and gaff were pressed against the shrouds.

I was also already thinking of adding an additional line to pull the sail down and adding a pole to run a large lightwind foresail. It might hve been the best to add another meter to the mast height right in the beginning to add a few m2 sail area.

[john james]

Wow everybody's got a lot to say about going to Winward - the most unpleasant direction you can pick to go,  in the right conditions yes a good romp to Windward is excellent -especially with other boats around and smooth water. BUT thinking of oceans ways I'd rather not. I think you should be gauging your speed by boats around you and you should be about as good as a moderately good mono-hull. Off  the wind of course the fun begins.A Clean bottom is probably the most important consideration determining performance  of any multihull

[Rory McDougall]

Hi Bart

Yes, I will just repeat all the points that have already been made!!

All are right with having a clean bum! Wharrams have a large wetted surface area of hulls compared with other cats. So cleanliness is a must. The Tiki wingsail rig needs to be powered up to sail efficiently to windward. Cookie comes alive when wind gets above 12kts. I can get true angle of 40-45 to the wind. Add leeway and I average 45 degrees to windward. As seas get steeper and rougher this angle gets worse as leeway increases when boat is stopped in waves.

-Get good rig tension for tight forestay.

- Try using windward jibsheet to barberhaul the clew of jib in a few inches and see how it helps pointing angle.

- Get heaps of tension on peak halyard for going to windward. Dump mainsheet. Haul on peak halyard. Sheet in and fly!

- As wind gets up, reef jib first before reefing main to keep aft sail area driving the boat into wind better. A bigger jib than main will pull bows to leeward over every wave.

- For new sails try Westaway Sails as well as Jeckells. Cookie has used just 2 sets of Westaway sails in 25 years = v.good value.

A final note to all having trouble hauling mainsails down when running before the wind. Raise the main in front of the shrouds for downwind. - No friction. No chafe. No hassles!

[Ian Bamsey]

This is an interesting discussion and Rory's figures are helpful. If I take Rory's 45° to windward to mean to the apparent wind, then in 10knt of true wind, with a boat speed of 5.5knt, the angle to true wind is about 68°, so a tack goes through 136°. These figure tie up with my 120°+ tacks and that reported by Bjorn.

I might be wrong on what Rory was saying? For example, sailing into 10knts true, at 45degs, with a boat speed of just over 2.8knt gives an apparent angle of just over 35°, which I think is very good, but might be possible, but I don't have enough experience to say.

These are all theoretic figures, but are revealing. The theory also tell me that if I'm sailing in 10knts of wind and making 4.0knt at 65° to the true wind, I will be sailing at 47.7° to apparent wind. If I want to maintain my bearing and increase my boat speed by 0.5knts, then the angle to apparent wind changes to 46.1°. So I need to improve my boat's pointing ability by over 1.5°.

I think it's time for me to get a 2:1 on the peak halyard and a down haul! I'm not sure about new sails, the wife would kill me.

[Bart]

First thank you all for the help and advice!  Last weekend i was sailing and trying to improve step by step.
It seems that one big ( the biggest?) shortcoming was my lack of experience with this rig, i pull the peak  higher now, that helps a lot. I still find the traveler difficult to work with, it needs to much power to adjust and i cant adjust it with the main sheet  tight. ( witch was very easy on my former quarter ton boat). the sail profile is improving  i think.But the deepest point of the sail is arround the middle, i thougt it should be arround 1/3 from the front? But it looks more or less the the same as the photo rory did post so it might be alright?

The vmg i get is also better, but still don't now if this is what is to be expected. ( see photo: apparent wind 14 knt, apparent wind angle 37 degrees, boat speed 5.8 knots vmg 3.1 knots) When compared with other boats i am upwind about as fast as an open 6,5 meter sharpy ( a "valk").

Tacking angle is still arround 70 degrees, a lot sharper than the 90 degrees angle i get from a quarter ton  boat. ( sailed a nice match with the  waarschippers club that same weekend). The 45 degrees as rory reports are a nice goal for next year i think...

Probably i need to practise a lot, improve the usability of the traveler and put a good layer of antifaul on the bottom.

Again,

Thanks for your thought and advice!

Bart

[Olivier R.]

Very hollow :-(

[Patrick John McGrath]

I am in complete agreement with Maxim about locking the jib halyard at the top of the mast.

I have ,in the past, lost two important overnight races when the jib halyard in one case ripped the mast cleat right out of the mast  and another when the halyard tore out of the deck jam cleat. The danger of a jib locked at the masthead is not very great as the jib sheet can always be released in a moment of danger.

As to the Wharram hulls, they have much less efficient hull section when relied upon to resist leeway.  Wharram catamarans can be improved in windward speed and angle by fitting  properly designed low aspect ratio fin keels.  Norman Cross's multi's are a prime example.

[Roger]

Ian. Here is Little Cat yesterday after I turned her to tack directly into the wind in San Quentin Bay (moving from left to right).At the start of the run the wind is a steadyish 10 knots and increases to 15 knots by the end (left). The boat is heading into a small chop, and the tide has just turned and is heading out (against the boat) at about 0.5 - 1 knot. The average boat speed is 5-6 knots. The vmg to windward is 3.5 knots. The tacking angle from the true wind is 50-55 degrees (100 - 110 degrees). I think this is a pretty good real world example given that the boat is heading into the tide. It supports my humble opinion that in ideal conditions (this wind, dead flat water and no tide) that a Tiki 21 can do square tacks, or close to (45 - 50 degree tacks).

Ian Bamsey said:

This is an interesting discussion and Rory's figures are helpful. If I take Rory's 45° to windward to mean to the apparent wind, then in 10knt of true wind, with a boat speed of 5.5knt, the angle to true wind is about 68°, so a tack goes through 136°. These figure tie up with my 120°+ tacks and that reported by Bjorn.

I might be wrong on what Rory was saying? For example, sailing into 10knts true, at 45degs, with a boat speed of just over 2.8knt gives an apparent angle of just over 35°, which I think is very good, but might be possible, but I don't have enough experience to say.

These are all theoretic figures, but are revealing. The theory also tell me that if I'm sailing in 10knts of wind and making 4.0knt at 65° to the true wind, I will be sailing at 47.7° to apparent wind. If I want to maintain my bearing and increase my boat speed by 0.5knts, then the angle to apparent wind changes to 46.1°. So I need to improve my boat's pointing ability by over 1.5°.

I think it's time for me to get a 2:1 on the peak halyard and a down haul! I'm not sure about new sails, the wife would kill me.

[Roger]

Sorry, the boat is moving from the right to the left, into the Bay.

[Ian Bamsey]

Hey, Roger that's interesting stuff and it's clear you're doing well to windward. I met Rory not long after I made the post about the angles and he confirmed the 90° tacks against true wind.

It's becoming clear to me that windward ability (and speed at any point of sail) is really sensitive to small changes in the boat set up and the skill of the sailor (or lack of in my case). I get the impression that this might be particularly true of catamarans and hence the reputation. I wonder also if cats' polar plots mean they increase their VMG to windward more quickly when they come off the wind than do many monohulls. Hence the monohulls see cats pulling away from them, but further off the wind than their own course.

Gratitude will be coming out of the water soon. As you can see from the last weekend's track, I'll have to wait until next spring to see if I can catch up with you and Rory!

[Roger]

"I wonder also if cats' polar plots mean they increase their VMG to windward more quickly when they come off the wind than do many monohulls. Hence the monohulls see cats pulling away from them, but further off the wind than their own course."

I think that is true for fast cats footing to windward (beach cats and performance multi's with tall rigs and boards), but Wharrams are slow cats and vmg has to be a balance between angle to the wind and adequate speed to minimize lee way.

If we are talking about close reaching wind angles, then I think you are right that a wharram sailing at speed can beat a bigger mono sailing a tighter angle at hull speed.