Historical multihulls

...just happened across this setting on my computer

CAT CRAZY, TRI FI
And Other Multihull Comparisons
By Jim Brown

 

Lucky man are you. These cats designed by Irens and made in 86 and 87 by J.F. de Premorel were very well built (carbon local reinforcement, kevlar and foam- the beams in carbon were incredibly strong and light), fast and safe.

The best for coastal cruising or a fast jump to England or Ireland from Brittany with a good meteo. Have you kept the 18m "pre-bent-stressed" original mast, or are you using a simpler shorter rig?

I have great souvenirs with the ex Data General/Aquitaine, like crossing the Fromveur at 16 knots against the wind, or runs of several hours at 20-22 knots in medium wind-flat sea with just a small mainsail of 75 m2, the leg on the tiller for governing, sipping coffee and discussing about thomist philosophy...Kept light, these catamarans are very fast with excellent mean speeds, but so well mannered at least for Data General with the special foil boards and big rudders.

 

Thanks so much for the original experiences, I've very little information from people who actually experienced the boats first hand back when they were raced. The mast is the 87 section (larger chord) as it was upgraded for the second year of competition, and is still 18m. Mine has the vertical boards, unlike DG, but also tiny rudders. The boards and rudders are the two items I intend to upgrade, along with the mainsail and boom, but I'm just going to enjoy it as-is for a few years and get used to handling it. Mine is only 1350kg at the moment, without sails on board, so still very light.

 

Nice video of Volage sailing apparently one of the first F40 catamarans

http://youtu.be/NdXSXS_aKcA



and some history on the boat linked from the video:

http://www.7seas-news.com/VOLAGE-Un...r-de-Belle-Ile-grace-a-la-passion-d_a300.html

 

https://www.youtube.com/watch?v=g-KeysmbTS4
Itś a short video with an Irens F40 which looks very closely to Data General. Visibly, it's keep almost in racing condition, with very expensive sails.

I've never raced in F40. That was out of my league, and my work did not left me enough time for any serious racing. But I have navigated several times on F40 (catas and tris), and other racing multis, and convoyed some of them. You do not take risks when convoying but you can have a lot of fun on a F40.
That I know from I has been said, it's like with all good race boats, it's very easy to get 90% of the performances, and very hard to get the 105% needed for winning.
Data in (fast) cruising was a very easy and forgiving boat; racing it was another matter as the boards could "pass" in negative, meaning that instead of uplifting the boat, the boards act as brakes and downlift the bows, that happened only when going over the limit with spinnakers. That a pretty dangerous situation, when the 2 bows are under 6 feet of green water and the sterns 15 feet above the water.
I have also helped to transform 2 F40 from racers to coastal cruisers. I mean "coastal cruisers", boats able to receive 3-4 guys in spartan conditions for a week with a large range of wind and sea conditions, from 0 to force 6-7.
The essential is to keep the boat light. It's not a floating condo... Amenities are kept to the minimum.
Keeping the ratio 9m2 jib and the 81 m2 mainsail is determinant as the boards and rudders have been calculated with that repartition. The common mistake is to use genoas, useless on a fast multi, and putting the center of sail to far forward.
The most efficient sail is the main as it can be very finely tuned using the rotation of the mast (with the "arthur"), the luff tension, the diamond stays tension, the leech tension, the main sheet tension, and the traveler on the track. A good jumbo (the speed led screen) is essential; you see immediately the effect of a tuning on the speed. A lot of small pennants on the main sail are a good help at the beginning.
When you make a few calculations of stability, you see that the weight of the 3 last meters of sail-mast on the 18 meters mast are determinant when the heel is over 15-20 degrees, even with a completely open main sail.
So in coastal cruising with no purpose of records or racing cutting the mast at 15 meters may be interesting for security.
The 2 transformed F40 used terylene sails, with 3 reefs, lazy jacks with all the ropes for reefing already installed. Reefing was a breeze. You know the fast changing conditions in Brittany...Terylene sails were cheaper, easier to tune and reparable.
The jib was pretty flat and heavy, as it can be used as storm jib, a track on the front beam and pulleys so you can almost forget it, and save 2 winches. I can say that in "convoyage" with only 2 persons there was no jib, and a 75 m2 terylene mainsail...
The spis, or better gennakers are rather small. It's very hard to get 27 knots and a lot of sail is needed, the 25 knots are easy with a small gennaker, and being very lazy and prudent you get 22-23 knots...
One of the boats foamed the mast so it actuated as buoy in case of turning over.

 

Thanks, I've seen that vid. I understand from here it is one of the 87 boats, ex Fleury Michon, which apparently had lower volume hulls, but look very similar to me. It does look in lovely condition, and I aim to get over to the west coast and see it this summer.

My boat came with two sets of sails, an old mylar racing set that are heavily worn, and a new dacron set (main, self-tacking jib, spinnaker) that have hardly been used. However, both are the old pinhead shape and fit the very heavy, much repaired boom, which I intend to replace, so the sails will need re-cutting, as a minimum, to match the shorter boom. I also have lazy jacks and reefing lines permanently installed as I will be shorthanded most of the time.

I have an airmar DAS to monitor performance, so will be interesting to see the effect of changes as we make them.

How did you find the boat handling without the jib?

 

You're right it's the 1987 Fleury Michon, which seems owned by Martib Guillaume. On the vids it seems in very nice shape.
Data/Aquitaine/Totem seems disappeared after 2010.

Mylar when worn is useless...you can keep it as model for a new sail, but most sailmakers, when experienced with multis, prefer to start from scratch.

Why do you want to put a shorter boom? Re-cutting the sails will be more expensive than a piece of alu tube, installing the hardware on piece of profile is a rather simple job. You can make a boom from any profile having enough inertia, taken for example from a broken mast.
Re-cutting a sail in its lower part implies a lot of work if you want to keep a good shape and strength. The results are never guaranteed. It's easier to re-cut the upper part. In 87 very round leeches were not mastered, it's common now even on beach cats with "cheap" sails.

Data was always convoyed without jib and tacked perfectly. But Data had bigger rudders than most of the F40, as it the boards took 75% of the lateral effort (anti derive) and the rudders 25%, so the center of lateral effort was behind the boards, which became the forward pivots for tacking.
As the jib is self tacking it does not take a lot of work even shorthanded. Generally in coastal cruising the jib is set and not more touched even downwind at least for the sheet tension. In fact the jibs were kept on the F40 catamarans only because a storm jib (tourmentin) was mandatory in the sail inventory. As you will see on your jib they were cut very flat, almost a bed sheet.

 

Loick Peyron is fixing up a sister ship of Mike Birch's Olympus Photo the Walter Greene designed trimaran to sail in the 2014 Route du Rhum. He is carrying out the work at Multiplast.

https://www.facebook.com/photo.php?v=823697620991236&set=vb.109933829034289&type=2&theater

 

My rudders are small, and something I would change if I upgrade the foil package. The boards on the 87 boats look to be further forward than on mine, so I suspect the board/rudder balance is different. The previous owner rigged it with a lot of mast rake, which will have loaded the rudders more than the design. The jib is, as you note, a flat blade.

I can replace the boom, but I would ideally like to discard it completely and use a stiff bottom batten/boomette, but this then requires the clew to be such that the angle to the mainsheet track is correct to hold the sail shape, which in turn requires a shorter foot, and hence move to a modern sail profile. The current aspect ratio is less than 3, I would like to achieve above 4, and the smaller sail plus removing the boom would save around 100kg (though a new boom would save nearly this amount - the old one is more than 10% of the total weight!).

I would re-cut the sails myself, but given that they are new Incidence sails I may try to sell them and start fresh. Dacron may be cheaper and long lasting but it is so heavy I would prefer to use a lighter material and accept the cost/life compromise.

 

After trials beginning of 87, the masts were heavily raked on almost all the boats. I would keep the original dacron sails, make a new boom and stay away of a too high ratio mainsail on a 1987 boat, furthermore single handed. the boat will become very hard to tune correctly and probably the mean speed will be lower.
Because of the limitations of the 1987 hull, the speed gain will be minimal, but the induced problems will be infinite, unless you have an expert team and a very big pocket. I would not touch the sails for nothing and I would keep the dacron if competition is not the main goal; it's far more forgiving, easier to tune and it's reparable. Surely a bigger winch for rasing the mainsail is cheaper than the transformation you want to make.
The drag curve of this hull goes almost vertical after 25-26 knots so no amount of added power will make it faster after 27 knots, unless you accept very big risks for one knot more. A faster hull needs less rocker, flatter stern and a different repartition of volumes, a very different shape. Look at the F40 cats now...
I would try to make a compromise;
The boat was designed for a team of five professional guys able to get the boat at 105% for a regatta, with assistance boats and all the help in eventuality of problems. That was the top in 1987, 27 years ago...
Now the boat is a collectible old lady, but able to give good sensations and fast enough to smoke 95% of the boats in 2014. You have said singlehanded, that means a safety compromise; maybe bigger winches, re-organization of the hardware as you'll have at hand the 3 more important things on a multi; mainsheet, gennaker sheet and the tiller while being comfortably installed with a good view.
As I said the 1987 Irens F40 were very easy at 20-22 knots, a bit harder at 23-24 knots and wild beasts over 25.
The rudders were put forward later because of 2 reasons; a smaller radius of gyration while passing the buoy and ventilation when pushing very hard.
For you it's better to keep the rudders where they are, and as you will be forcefully going slower than a 5 pro guys team and obliged to maneuver at moorings and marinas without assistance you may need bigger rudders. They won't be a penalty at 23 knots... It's a rather easy job; simply take the original rudder and add an extension of maybe 20-30cm of heavy foam and glass well faired. just the same chord but 20-30 cm longer. And not too strong, so it break if needed without damaging the original rudder.
The rudders were generally made in cedar, epox, and fiberglass.

 

Thanks for the news...a transat in the old fashion with an old lady.

 

Thanks again for the advice, it is much appreciated. I won't be making any modifications for a while, just enjoying the boat as it is and quantifying its current performance, as I have other projects to finish first, so when I do get to start modifications I'll have some experience and data to consider.

 

Have been finalizing editing, layout of the Jim Young book (he keeps asking me to change sections to different positions ... which mean the layout goes to hell and has to be redone). Anyway, he obtained this shot of his 40 foot Bladon Racer trimaran sailing up the coast from Tauranga; boat was designed way back in the late1970's, has large sail area double rig and water ballast tanks in floats, plus quadrant boards there too. The leeward water ballast automatically emptied. He always was ahead of the game.

 

So is that technically a schooner rig, with the aft mast taller than the forrard??

So it's not a typical mono ketch rig, right?

Apart form the increased sail area, is there any particular advantage / disadvantage to this rig?

 

hey Ray, Jim calls it a sketch/ half schooner/ half ketch but really it is similar/same as Tabarly had on Pen Duick IV, two equally sized mains. There were a few, very few, schooners with equal height masts. Here's the rig profile. The advantage is very large sail area low down, excellent for hard reaching in fresh wind.
Cox's Bay Skimmer has same rig setup - am biased but can't see any disadvantages; fast to windward, points high, dynamite on a reach, better stability than tall single rig.