build a wharram or a Prout 37?

Some interesting points here - thanks

I did some searching in my "library" and came up with some pics of hull shapes "old" and "new"

When you look at a modern hull and compare it to a Prout or Dean you realise that a Prout is actually some kind of a tri and a Dean is just short of raft/barge. The slamming under full load must be huge - no wonder that these designs could not carry load and had to be kept light because the boat in itself was already very heavy.

Even the smallest Easy is MUCH better. I think that the designers have learned over the past 30 years that high bridge deck clearances of 700 mm is preferable even with the added penalty of windage resulting from the high bridge deck cabins. Modern Cats at 38/40 feet weigh around 3500 kg's and can be loaded another 2500 kg's to an average total of between 6000 kg's and i have seen up to 7000 kg's

The aft mast concept is very appealing to many cruisers - and it will always have its criticts, however i think that the aft mast on the Prout and Dean was often blamed when it was in fact poor hull design which led to slow boat that were no faster than a mono. 30 years ago you were considered stark raving mad if you even thought that a cat could reach 20 knots - this video proves that the modern cat has truly come a long way

http://www.youtube.com/watch?v=lsTXGhN3rLU

this info will clearly show that Prout - Dean - Wharram designs are past there sell by date, if you can pick one up at a good price that is in good condition, dont hesitate GO FOR IT, to build NO NO NO, you can build a modern design CAT with dridge deck clearance of 600 to 700 mm which will result in a far better boat

 

thanks guys -

Some great analysis there - touble is I'll probably never be able to afford the materials and plans to build a great modern cat, but the prout may have been possible.

Perhaps sold it afterwards.

However, I am convinced and will try to think of another way

 

Jah

that Prout would have sucked you dry and you wont get your money back - the old shitty stuff is going very cheap nowadays

dont lose faith
start with something small that you can sleep on
the big thing that i have seen is to get to the water first
a small build is fun and you can do it bit by bit as you have money
when you get to the water the **** hits the fan
it blows - it rains - it gets cold -it's too hot
bye bye wife/girlfriend and many friends
if you still go back, even alone
welcome - you have got the disease

here is something very cute that is do-able

http://www.paul3507.pwp.blueyonder.co.uk/


I absolutely love the Tideway14 at the bottom of this page

http://www.selway-fisher.com/PCup16.htm
http://www.selway-fisher.com/BoatBuilder.htm

and here is a huge page with one of the best backup and information forums around

http://www.bateau.com/index.php

and also this

http://www.glen-l.com/

if all of this doesn't get you hooked nothing will

happy reading - it will take many months

 

Sorry to answer so late; As the main sail is the almost lone sail in such configuration, reefs are taken soon (at the difference from a monohull when you change the genoa for the jib #1 and so on) so the load on the main sheet does not increase fiercely. A mainsail is easy to control compared to a jib, as illustration you see a boat like the trimaran IDEC where a lone main can control 350 m2 of sail, even in the 50ties in South Pacific...

 

Manie,

Multihull Design has changed a lot. I can say that a cruising design older than 15 years is totally missing the last developments. It's not simply the height of the bridge, but also the weight, the rigidity of the structure and most important a very different hull: the repartition of volumes and surfaces, prismatic coefficient, and position of the centers. Add the appendices and sail rigging. The lone thing in common between a 20-30 years old multi and the last ones is the number of hulls...

Aft mast was abandoned simply because this design is not efficient on a modern multihull. Jibs require a lot of hardware and can't be set closer enough to the center of the boat, so at each acceleration the jib will lose the wind and stall. That gives the characteristic of old multis accelerating, attaining a certain speed and decelerating because the big jibs are stalling instead of keeping the speed (hydrodynamic problems of the old hulls participate also in the speed "yo-yo" problem that plagued old multis).

The efficiency (the Cz in aerodynamics) of a modern fully battened mainsail is far better than of any genoa or jib. You have a fully controlled shape by the mast, boom and battens. Compare it to the sagging triangle of cloth that is a genoa which is changing of shape because of the deflection of the headstay.

The best proof of I'm saying is to look at the rigging of all the modern multis and specially the racing ones, and the average speeds they attain.

 

Thanks again guys

Manie,

Thanks again.

The multihull idea is to get the wife sailing; even keel , deck area etc.

I have been sailing quite a few years and did all my own work, including launching & recovering (built own trailer to ensure bearings never got wet - and that was for a bilge keeled monohull). Even dug my own mooring and made my own mooring anchors.

I certainly know how to go about something the difficult way !

I now just dinghy sail monos and catamarans. Do the odd delivery now and again. Delivered an Oyster a while back (very luxurious yacht in uk) that was an eye opener - lots of things went wrong on a newish year old boat.

I think I just meed to save up more pennies.

Fair winds to you all.

 

You can use the same amount of materials to build a dog as it takes to build a cat.

http://boatcraft.com.au/Shop/index....=32_33&zenid=bf6dd78947ac609efbbff7701b70b676

Simpsons are a great boat (I am biased) plans are cheap and there is nothing exotic or difficult in the construction .

Strip planking hull to deck joins can add a more rounded modern look to a hard edged older design.

 

sabahcat re simpsons boats and plans

i am familiar with that webpage but i have never come across any pics or write ups of completed boats

have you any websites i can visit ??

thanks

 

There is small mention of one here http://www.themultihullzone.com/workshop.html The Australian boat mentioned was mine (she is now in New Cal and we sailed her over). and we are currently building a modified Simpson Slipstream 50 as a low powered powercat.

( http://www.boatdesign.net/forums/profile/catmando2.html This is me, lost logon and changed email meant change in name )

We have seen many 10.5's out there cruising, they are the home built version of an Inspiration 10, which is the production version from the same designer.http://www.catamaransaustralia.com/ a very popular and spacious cruiser/charterboat as was the Elite range of catamarans http://www.tasmancatamarans.com/catamarans_c-40.htm

In my opinion they are a good safe boat that if built diligently trying to save weight all the way can be a fast boat, mine was a rocketship.

By adding radius's to hull to deck joins and cabin side-roof joins its easy to achieve a modern look from an arguably dated but classic styling.

They were designed with ease of build in mind which is why they are a bit straight.

 

sabahcat

nice links and nice boat
please post more pics of her sailing
what kind of speeds at what wind ?
displacement finally ?
where all did you sail her

are they also built with a 9mm marine ply outer skin (12mm at the bottom) covered with 1 layer 400 gm glass and epoxy outside and basically taped on the inside joints with 100 mm x 200 gm tape and covered in epoxy inside ?

 

Thanks

of all the years we had her, we only managed to get 2 pics of her sailing as we blasted past another cat

She could manage wind speed easily enough on the right angle up to about 12 knots, then sea state and waterline length started to affect her.

In 3 to 5 knots of wind, working the sails you could match wind speed accelerating in the puffs and stopping in the lulls without enough weight to carry her to the next bit of wind.

Up to 12 knots she could match it on a reach but would do 7's easily enough uphill.

12-20 she would sail around 12 on a reach surf up to 17 and go uphill at 8 maybe 9 depending on sea state, (working jib uphill at 12 knots windspeed first reef at around 17 knots of windspeed)

Above that it was brakes on time reducing sail to match seastate., but we did have 25.9 knots of boatspeed burned into my brain once surfing across wide bay bar in big weather.

is around 2800kg to DWL from memory full load and I think she would have weighed around 2000kg at launch

Qld Coast and reefs and to New Caledonia for her new owner

She was strip plank design, specs were for 12mm WRC, 220 uni in and 440 db out, we went 10 mm WRC and 400db in and out with designers approval, if doing her again I would go 10mm with 400db and 220 uni, saving 400grams/m2 straight up.

She could have been done with Ply sides above the knuckle, but I was in a planking frenzy by then. Decks, BH and furniture were all ply Cabin was WRC, Bridgedeck, extensions/mods were of foam filled honeycomb.

 

I feel I need to put in some kind of defence for the Prout. My parents had a Prout 34 for many years and later a Dragonfly 920 Extreme trimaran (a truly fast boat).
I sailed the Prout a few times across the English Channel to France, Belgium and Holland and motored through the canal systems before sailing home again. The advantages of the Prout are that it is spacious, solid, seaworthy, easy to sail and performs adequately. My parents boat had in-mast furling for the main, which requires main with no battens and is therefore pretty awful from an aerodynamic point of view. However, it was still capable of 11-12kts downwind and 7-8kts upwind, which is good compared to most monohulls. It didn't point brilliantly (maybe 50 degrees), but it wasn't awful, and this is as much due to the lack of daggerboards as anything to do with the rig. The Prout has skegs which give it a very shallow draft and take up no space inside the boat - we were able to sail over the top of sandbanks on passges to Belgium, which saved many miles compared to monohulls and daggerboarded cats that need to sail around them. It must be said that every single person I know that sailed on it was sick the first time as the motion is unusual and 'corkscrewy' (port bow, stbd bow, stbd stern, port stern), but after one day you get used to it and feel fine. Of course, like all cats, you have the advantage of sailing upright all the time. The vast majority of the time the Prout was just sailed by my mum and dad. My dad has always been a keen sailor, sailing cats and dinghies all his life. My mum has never sailed before my dad decided to give up little boats for bigger ones. Basically therefore, they sail one and a half handed - my dad does nearly everything and my mum helps if required, putting out fenders at marinas etc. My dad never had any problems tacking or controlling the boat. The Prout wasn't perfect (what boat is?), but it was a good boat. Personally I would have like a better mainsail, and would look to reduce weight (my parents carried a load of junk with them!). I would also prefer a mesh trampoline up front rather than a solid cover, but then you would lose some stowage space.

In contrast, the Dragonfly is much more like the kind of boat Ilan Voyager is recommending, except it is a tri, not a cat. It was an absloute joy to sail with its lightweight and efficient rig and would do 12kts upwind in a force 4, and downdind was ballistic. My dad loved it, but was less able to sail it his own and needed more help from my mum. My mum found it too physical and scary. They only kept it two years because, as nice as it is, it was harder and less practical to sail and therefore got used a whole lot less.

I suppose, in summary, that the Prout was the better boat for non-sailors and the Dragonfly was better for 'true' sailors. The Prout could be left to do its own thing pretty much, the Dragonfly (and many higher performance cats like Ilan Voyager is advocating) needed constant attention, much like a beach cat. So it depends on what you want the boat for, to decide what type of boat is best.

Nice looking boats by the way, Sabahcat.

 

Thanks PI for your opinion. The Prout was good by the standards of its period but cat design (and other multihulls) had a major evolution since (passing from the Prout 34 to the Dragonfly it's a major shift...I imagine the change for your mom...)

It's why I called the Prout "antics" and in 2009 I do not see the fact of building an "old fashioned" cat as a wise decision. For the same amount of money and work (and maybe less) you can get a better cruising cat, with better value of reselling. By cruising cat I mean a spacious boat with comfortable amenities, but with enough performance to cruise "quietly" without getting bored. A lot of modern designs can do that.

A fully battened big mainsail is the best "engine" for a multihull (it's so efficient that some monos -look at the last Van de Stadt designs- use it). The common mistake is to under-size the hardware of the mainsail, thus making its control difficult. With the proper hardware it's fast, easy and secure as you can depower this mainsail (in every sense of the word) in two seconds.
On a cruising boat an automatic device can be used to release the sheet of the main sail in case of heeling beyond a certain angle.

I'm not recommending a tri like the Dragonfly for cruising, or a high perf cat; a such boat would be exhausting in a long cruise. A more placid boat is needed, but with better behavior and performances than the old designed Prout.

For a cruising cat or tri, generally it pays to to optimize the ratio length/weight (and load)/sail surface, with a moderate width. Thus you can use simple techniques for the building of the boat as plywood and strip plank and get sufficient perfs with a simple rig.

Rigging and sails are the most expensive part of a sail boat; it can skyrocket when you are going to carbon fiber masts, Mylar kevlar sails and to the big hardware like furlers, 3 speed big winches and so on.

It's in a such optimization that a good NA earns its money.

 

Thanks Ilan. I agree that there are undoubtedly better designs since the Prout was conceived, but as JAH has access to moulds for the Prout, it makes sense to stick with that if possible. The Prout isn't terrible, in fact it is perfectly okay, its just not the latest thing. By modern catamaran standards it is heavy and slow, but compared to almost any monohull it is still quick and light!
If I had the pleasure of buying a new boat, I'd take a good look at the Catana catamarans. They look great and I think are much closer to what you describe, but cost a fair bit.

 

Quote:- guindant = luff, thus I think you're talking about the tension on the main halyard?

Do you mean a 'Cunningham' downhaul?

Another quote from Wickipedia:-
"The tension in the luff of the sail is adjusted using a combination of the halyard and the cunningham (where fitted). The primary advantage of adjusting the cunningham is the speed and ease with which the luff tension can be changed while sailing or racing. By hauling or easing the line, the tension in the luff can be changed, thereby shifting the point of maximum draft of the sail forward or aft, optimizing sail shape—and therefore—performance. It is a fine control which is used more frequently on racing sailboats than on cruising or day-sailing boats.