The Prout Debate

[Southern Star]

Yes, we will have to disagree. There are many current cats that are anything but overweight, floating condos, including ones intended for performance offshore sailing and I don't know of a single one that is a double-ender.

While stability obviously requires consideration of the sail area and Ce of the sail plan, those factors are independant of the length to beam ratio. In any event, we were discussing the impact of hull design on stability and not of the sail plan.

I quite agree that the wide sterns and relatively flat aft sections on open 60's were intended to assist in carrying large sail areas while sailing downwind (and to permit surfing in certain conditions). However, these same design attributes (as well as twin rudders) also make the boats much less susceptible to broaching than most other monohulls. The point is that broaching is not a significant problem in catamarans for precisely the same reason - significant beam aft and twin rudders. Obviously a cat with short, inefficient rudders and keels might still be susceptible, but that has nothing to do with transom design.

I am glad you at least agree that transom sterns are 'excellent' on cats and tris if properly proportioned. Indeed, for the reasons discussed above, most (if not all) naval architects believe that they are better than double-ended hulls that are also properly proportioned - increased bouyancy aft and a typically higher prismatic coefficient lead to better stability and higher performance. Is a lightly laden, double-ended cat with properly-proportioned hulls likely to be more sea-worthy than an overloaded cat wtih fat hulls and wide, sunken transoms? Of course. However, when discussing hull design we should be comparing apples and apples.

Cheers!

Brad

[smj]

Originally Posted by Sand crab

I never knew the Solaris Sunstar 36 was a Lerouge design so I just looked at it and it is very Manta-ish. I like the way it looks, too. It has better lines than the 42.
Good posts Southern Star.

Don't ever make the mistake of telling Mr. LeRouge that the Sunstar and Manta are his designs because he will strongly deny it. The Sunstar was pulled from the old Jeffcat32 molds and I believe the Manta had its molds pulled of a Jeffcat 42. Both Jeffcats were Eric LeRouge designs but both the Sunstar and Manta were built WAY heavier than LeRouge would have agreed to. I've been told he's not very happy as the Original owner of the Manta didn't have permission to use his design.

[Cavalier MK2]

Cheers to James Wharram and Hanneke Boon for avoiding the trends. There are great cats out there but it is up to the buyer to find the right combination for the sailing they intend, being better informed about everything certainly helps. It is important when contemplating a boat to find out what it was designed for and to keep within those parameters.

Cheers, Cav

[Southern Star]

smj, I too have heard that Lerouge was unhappy about the weight of the Sunstar and the Manta and, while he may not have profited from the sale of either boat, the original molds were certainly his designs! And Cav, while I had not realized that James Wharram was still designing new boats (how old is he now?) and, while I have not heard of Hanneke Boon, I too cheer people who are prepared to buck trends and design for a limited market - lets face it, you and others make it clear that there is still a market for double-ender catamarans!

Brad

[boatman61]

Originally Posted by Southern Star

smj, I too have heard that Lerouge was unhappy about the weight of the Sunstar and the Manta and, while he may not have profited from the sale of either boat, the original molds were certainly his designs! And Cav, while I had not realized that James Wharram was still designing new boats (how old is he now?) and, while I have not heard of Hanneke Boon, I too cheer people who are prepared to buck trends and design for a limited market - lets face it, you and others make it clear that there is still a market for double-ender catamarans!

Brad

Hanneke Boon is the other lady who accompanied James across the Atlantic on the first 'Tangaroa' back in the 1950's... she's been an integral part of his design/building team ever since. In fact she does/did most of the drawings..
But then again it could all be a figment of my imagination..

[Cavalier MK2]

Actually Hanneke Boon came along later, the daughter of a Dutch mathematician. You guys do have pretty big figments! Check out the Wharram website and update about their cats. Many transom cats are functioning as double enders because the transoms are clear of the water, for the light air drag thing.

I could see why Mr.Lerouge might be upset, if a boat is heavy it won't work the way it was intended and if he wasn't involved he won't be getting a design fee. So plan accordingly and be honest about potential handling, loading and performance issues before overloading these boats further. I do like many of the early French cats back when they were streamlined and designed to sail but haven't bothered to see how they are holding up. Might be worth the look for the budget minded with a more continental sense of style.

[boatsmith]

I like double ended cats and cats with transoms .

[Southern Star]

I'm not sure about a 'continental sense of style', but IMO some older French boats such as the Lagoon 37 were not only attractive, they were also solidly built, had excellent bridgedeck clearance and very good performance.

No, cats with transoms out of the water don't function quite like double-enders because they have substantially more reserve bouyancy in following seas: as the water rises above the waterline, the volume of the hulls increases much more rapidly than on a double-ender due to the additional beam aft.

While the Sunstar and the Manta were heavier than Lerouge would have preferred (and lets face it, how many cats make their design weights), nevertheless both were well constructed and have proven quite durable. What's more, as I am sure SMJ can confirm (as a previous owner of a Sunstar 36), the performance was decent and the motion in heavy seas benefitted from the typical Lerouge-designed tunnel shape.

Cav, one area where we agreee is that overloading a cat is a great way to reduce performance and to increase pounding. We can also agree that for offshore passages, storing a dinghy on davits is not the safest practice. No, I am not slavish to weight reduction on a cruising cat (and I have a decent array of solar panels mounted aft on the davits as well as a wind generator and radar ), but I have gone against the flow by purchasing a dingy with an air floor rather than a RIB: this allows me to readily deflate, fold and store it below for any passages out of protected waters.

Would my boat be quicker and have greater bridgedeck clearance with a smaller house battery bank, without solar panels,a wind geneerator, radar, below-deck autopilot, refrigeration, miocrowave, hot water, a full cockpit ensclosure, watermaker, spares - heck, with no dingy at all? Without question. However, those are compromises that I am not prepared to make. Nevertheless, as to ultimate stability, increased weight below the Cg actually increases capsize resistance and, to the extent that weight is largely kept out of the ends (e.g., storing my dinghy below and moving my anchors down into central storage compartments below the waterline when offshore), it has minimal impact on the risk of pitchpoling.

Brad

[boatman61]

[QUOTE=Cavalier MK2;1422405]Actually Hanneke Boon came along later, the daughter of a Dutch mathematician. You guys do have pretty big figments! Check out the Wharram website and update about their cats. Many transom cats are functioning as double enders because the transoms are clear of the water, for the light air drag thing. QUOTE]

Well there ya go... but then I'm not big on research just know I like Wharram Tiki's and Hanneke's been around as far back as I can remember..

[Boatguy30]

Originally Posted by boatsmith

I like double ended cats and cats with transoms .

Whatever the customer wants, right?

[Boatguy30]

Originally Posted by smj

Don't ever make the mistake of telling Mr. LeRouge that the Sunstar and Manta are his designs because he will strongly deny it. The Sunstar was pulled from the old Jeffcat32 molds and I believe the Manta had its molds pulled of a Jeffcat 42. Both Jeffcats were Eric LeRouge designs but both the Sunstar and Manta were built WAY heavier than LeRouge would have agreed to. I've been told he's not very happy as the Original owner of the Manta didn't have permission to use his design.

This seems to be a common problem with other designers as well in this sized cat. When a somewhat performance design is condo-ized by a production builder the end result is never up to the designers original claims/ hopes. I guess the reality is that smaller cats involve major compromises.

[smj]

Originally Posted by Boatguy30

This seems to be a common problem with other designers as well in this sized cat. When a somewhat performance design is condo-ized by a production builder the end result is never up to the designers original claims/ hopes. I guess the reality is that smaller cats involve major compromises.

I agree, but I think the problem with the Sunstar being overweight wasn't from condo-izing but just being way overbuilt. She still performed well and was probably the strongest cat we've ever owned.

[Cavalier MK2]

Sounds like we have some consensous and I applaud SS for taking the time to understand his boat, I must say those out of the water transoms do function like a double ender but since the out of the water end has been cut off the buoyancy is reduced!

I like them all too but have a soft spot for the older Prouts. And that CSK on the cheap multi thread. I used to see that boat years ago in Port Townsend and always thought it blew in from Hawaii. It was painted grey back then, always wondered where it went. Now if I had that 50 grand my cat sense would be satisfied.....thank goodness for the Nicol.

[boatsmith]

Originally Posted by Boatguy30

Whatever the customer wants, right?

We don't build anything I don't like. People who get invloved with me to the extent required to start stroking checks seem to like nice boats. Double ended, transomed, mono ,multi. There oh so many nice boats in the world.

[Southern Star]

Cav, you say that "those out of the water transoms do function like a double ender, but since the out of the water end has been cut off, the bouyancy is reduced." If your Prout had significant rear overhang, your point would at least be arguable - as the waves rose from astern, the volume of the hulls would increase on an additional plane (fore and aft) adding to bouyancy. However, as you have no rear overhang, as the waves rise from astern the volume of the hulls increases only slightly due to the V-shaped underbody aft. Most modern cats have u-shaped underbodies aft and when waves rise from astern, the volume increases much more dramatically as the previously elevated transoms become immersed in the water. My point is (and has been) that this added bouyancy aft improves not only fore/aft stability, but the ability to carry the equipment aft that most modern cruisers wish to carry. This, of course, is to say nothing about the fact that transoms and a u-shaped underbody aft also tend to increase the prismatic coefficient and reduce wetted surface, both of which improve performance.

Yes, I have 'taken the time to understand my boat', but also other boats and the reasons for various design attributes. The virtually universal move away from the polynesian-style, double-ended, v-shaped (or 'modified' V-shaped) hulls that dominated the early catamaran designs of the 50's and 60's is one that was based upon sound principles of naval architecture.

Brad