[sailingdog]

Here's a illustration of a monohull pitchpoling... not quite the same as what happens on a multihull, but close enough to give you an idea

 

[sailingdog]

While this is possible in theory, it would probably make for a pretty pathetic sailboat. Having so much weight concentrated in the deck structure would tend to raise the center of gravity and make the boat less stable to begin with-which is probably why there are no four-hulled boats out there.

The main hull on a trimaran provides a pretty solid foundation for the crossbeams when properly designed. The bridgedeck on a catamaran is also relatively easy to engineer properly. I'd point out that some catamarans have a very rigid bridgedeck, especially the full-bridgedeck designs, but other catamarans, like the older Polynesian based designs are a bit more flexible.

Well, if the hulls are used as feet for deck structures like the SWATH....
So they all could be of the same design, and with the big deck structure it's easier to have them rigidly fixed. Virtually a big ship on four feets. I guess it would be very big for better deck to hull structure ratios, and many tension structures.

 

[TSOJOURNER]

I see, thanks.

It seem someone has already registrated a patent on something similar:
International patent WO 94/20359
It's a trimaran with spaces midship of the hulls allowing waves to go through, hence, decreasing wave pressure to the hull (I think).

On another point, it's been said that multihulls have bad manoeuvering.
Is there any ship using a rudder at the keel to improve that?
(similar to canards for aircrafts; future ship will probably use propulsors, though)
Also would an arrow arrangement for a trimaran improve manoeuverabiliy?

 

[sailingdog]

Multihulls, especially catamarans with dual engine setups, can be very maneuverable. A large catamaran with dual engines can spin almost in place by skid-steering with one engine in forward and the other in reverse. Under sail, the dual rudders help with steering, but the dual hulls can make turning a bit more difficult.

Trimarans tend to turn and handle much like monohulls, as they tend to pivot around the central hull, much like a monohull.

An arrow configuration for a trimaran would be a disaster. The three hulls must be essentially parallel and generally located athwartships from each other. Some designs, which had shorter amas, which were mounted aft of the bow of the main hull, had a greater tendency to pitchpole, since they had insufficient buoyancy in the bow.

On many trimarans, the forward buoyancy is really supplied by the amas, not the main hull. The Dragonfly 28 is an extreme case of this, and it has the amas actually starting forward of the main hull's bow. This is probably due to the very high mast and amount of sail area the Dragonfly 28 was designed with.

 

[Triquetra]

I have a kind of hybrid trimaran, a Corsair 36, which I have fitted out as a liveaboard. Space is a bit tight at times, and docking does have to be carefully arranged, due to my 29.5-foot beam, as CBinRI alluded. It has been a bit of work to make it a liveaboard, as I have hull 16, but I think it has been worth it, and it is nice to be able to sail in small puffs of wind when others are motoring their sailing vessels. There are some other features that have not been mentioned about trimaran handling, which I have learned through experience. Since there is not much hull under water, turning at speed is great with the daggerboard cutting into the water, but at low speeds, you are at the whim of the currents and wind, since there is not much area directing the steering. Also, at anchor, my trimaran moves with the wind, not the current, so at places like St. Augustine, as the other boats orient north-south, I found that I was oriented east-west, and other boaters do not anticipate this when anchoring nearby. Also, I tend to sail a hull at 7 knots, and at 16 knots the windward ama is about 3 feet out of the water, which means that anything not tied down is in the passageway. I really enjoy her, and every day is a learning experience.

 

[sailingdog]

Just curious as to which Corsair 36 had a beam of 29.5'. IIRC, the Corsair 36 had a beam of 25' 7". Also, why do you consider the Corsair 36 a hybrid trimaran?

I have a kind of hybrid trimaran, a Corsair 36, which I have fitted out as a liveaboard. Space is a bit tight at times, and docking does have to be carefully arranged, due to my 29.5-foot beam, as CBinRI alluded. It has been a bit of work to make it a liveaboard, as I have hull 16, but I think it has been worth it, and it is nice to be able to sail in small puffs of wind when others are motoring their sailing vessels. There are some other features that have not been mentioned about trimaran handling, which I have learned through experience. Since there is not much hull under water, turning at speed is great with the daggerboard cutting into the water, but at low speeds, you are at the whim of the currents and wind, since there is not much area directing the steering. Also, at anchor, my trimaran moves with the wind, not the current, so at places like St. Augustine, as the other boats orient north-south, I found that I was oriented east-west, and other boaters do not anticipate this when anchoring nearby. Also, I tend to sail a hull at 7 knots, and at 16 knots the windward ama is about 3 feet out of the water, which means that anything not tied down is in the passageway. I really enjoy her, and every day is a learning experience.

 

[Triquetra]

As usual, you are correct. I must have gotten the folded 9'5" foot confused. It is 25'7". Now, I am going to worry about not having enough beam.

 

[scottyt]

dog you own a telstar and i dont know if you have been in a corsair 28, but it looks like they have more room in the corsair. do you feel the same?

now i do like the tri look but the space issue is a turn off for me. i would love to see performance sailing give the telstar a v berth. heck my 27 foot hunter is a lot bigger inside. i saw the corsair is a alot pricier, but i would think if PS made a 31 or 32 footer with a v berth ( basicly a more mono hull interior layout ) and could keep the price under a 100k the would sell the heck out of them. what do you think the extra 3 or 4 feet would add to the cost?

 

[TSOJOURNER]

An arrow configuration for a trimaran would be a disaster.

On many trimarans, the forward buoyancy is really supplied by the amas, not the main hull.

I didn't realize that. I guess it's a trade off for the necessary bow design of multihulls.

Also, at anchor, my trimaran moves with the wind, not the current, so at places like St. Augustine, as the other boats orient north-south, I found that I was oriented east-west, and other boaters do not anticipate this when anchoring nearby.

I see. Yeah, relatively more boyancy makes it too light for the elements.
I would be nice to have it transform to a monohull. :lol:

Anyway, now I know and understand lots more thanks to all your explanations and illustrations. I'm satisfied for now. Thanks a lot.

 

[sailingdog]

Yes, I own a Telstar and one reason I do is the Corsair 28 has a ridiculously small cabin-given that I'm only 5'4" and I can't stand up in the cabin of Corsair 28.

In some ways, the cabin of the Telstar is bigger than that of the Corsair 31CC, primarily because of the difference in where the head is. In the Corsair 31CC, the head is amidships, in the Telstar it is forward. That allows the main cabin on the Telstar to be much larger than that of the Corsair. However, Corsair 31CC does effectively have two cabins to sleep in-the v-berth forward and the aft cabin.

If you're serious about getting a trimaran in the mid-30' range, I'd recommend you look at a semi-custom one like the Chris White designed Hammerhead 34, which I posted a drawing of above.

The Hammerhead 34 has an aft cabin with a double berth, and a forward cabin with a single, as you can see here. The head is all the way forward, which might make it a bit uncomfortable to use heavier conditions, but it looks like a reasonable compromise. IIRC, it is design to be folded for trailering and storage, but I don't know the specifics of the design. I actually am hoping to speak with Chris regarding the boat for a friend of mine.

dog you own a telstar and i dont know if you have been in a corsair 28, but it looks like they have more room in the corsair. do you feel the same?

now i do like the tri look but the space issue is a turn off for me. i would love to see performance sailing give the telstar a v berth. heck my 27 foot hunter is a lot bigger inside. i saw the corsair is a alot pricier, but i would think if PS made a 31 or 32 footer with a v berth ( basicly a more mono hull interior layout ) and could keep the price under a 100k the would sell the heck out of them. what do you think the extra 3 or 4 feet would add to the cost?

 

[scottyt]

i do like the layout of his design. do you know what they run?


as for for being 5'4" that makes you a sailing puppy

also i will be up your way this weekend, i have to go bury my grandmother in yarmouth. how is the weather?

 

[tdw]

Have just spent a few weeks wafting around Jervis Bay (south of Sydney) where the only all weather anchorage is up Curumbin Creek with less than 1.5 metres over the bar at times. Not surprisingly there are an awful lot of multis in that neck of the woods.

Seawind factory is not far from JB and there are a fleet of them down there. Certainly they look the goods from a distance, give every indication that they sail quite well and that they have more than adequate accomodation.

Now I am not specifically anti multihull. Yes, all my boats have been mono but if I felt a multi suited my needs I'd have no worries going with one.

My major negative is that many (if not most) of the modern multis have interiors that are horridly plastic. Imagine2Frolic's is one of the nicest I've ever seen but some of the others...blech !!

I'd think also that one of the multis biggest drawbacks is size. It seem from what I read that anything much under mid to late thirties (feet) is not all that desirable. A forty foot cat for two people is an awful lot of boat, a large part of which is simply taken up by a plethora of berths which you cannot use for storage due to the need to keep weight out of the bow. Any comments of that ?

Specifically to you Dog......ignore the fact you own a tri......if money was no issue....Cat or Tri ? I am talking live aboard cruising here...not for a weekender, not for a marina bound floating condo.

Generally.....why don't multis have gimballed stoves ? I realise that they don't heel like a mono but even so I would have thought that on any small craft a gimballed stove would still be a good idea. Thoughts ?

Last but not least there is also a distressing tendency for cruising cats to have curved settees in the saloon. Useless horrid damn things they are. OK so when you are tied up to the dock they might be tolerable but I cannot for the life of me understand how anyone can get seriously comfortable on a curved settee. Maybe it is just me but I like to to be able to lie down not sit on a boat other than when eating. I may be bent but I am not curved.

 

[scottyt]

TDW you did not ask me weither tri or cat but i will answer anyway. i would answer what ever boat that looks, does, sails how i like. i think the lay out of the telstar sucks, i like having a vberth, i dont want to have to convert my table to sleep the wife and i. i have never sailed on a cat or a tri, but i have been on a few cats. i like the space, i like most of the layouts. yes a 40 foot cat is huge and a lot more than i would need. i would love to have an updated hull shape the size of a catalac 27, with standing room in the saloon. it would be about perfect for me. now i do like monos, and would love a mid 30's boat, maybe as big as a 40 footer.

as for looks each boat and i mean each model not just type makes a lot of difference. some tris i dont like the looks of, some cats too. from the pics i saw of the dragonfly i like it a lot. i like the looks of the gemini 10 and i like the inside a lot, but i dont know how i would handle the 30 second tacks ( this is a hink for chuckles to take me for a ride )

 

[sailingdog]

According to a recent e-mail from Chris, the Hammerhead 34 runs somewhere between $70-100k as a rough estimate.

Saturday should be nice, but a bit cool.

i do like the layout of his design. do you know what they run?

as for for being 5'4" that makes you a sailing puppy

also i will be up your way this weekend, i have to go bury my grandmother in yarmouth. how is the weather?

 

[tdw]

TDW you did not ask me weither tri or cat but i will answer anyway.

Scotty , feel free. My 'specifically' was not meant to be exclusive of others but I did want SD's take on it.

Now ref the Dragonfly....yep I like a lot about them as well except for the teensy weensy galley, forget that, I like to cook while the aft cabin looks useless for anything beyond a bit of storage. I'd reckon an aft cockpit DF could well be a fantastic boat.

 

[sailingdog]

Have just spent a few weeks wafting around Jervis Bay (south of Sydney) where the only all weather anchorage is up Curumbin Creek with less than 1.5 metres over the bar at times. Not surprisingly there are an awful lot of multis in that neck of the woods.

Seawind factory is not far from JB and there are a fleet of them down there. Certainly they look the goods from a distance, give every indication that they sail quite well and that they have more than adequate accomodation.

Now I am not specifically anti multihull. Yes, all my boats have been mono but if I felt a multi suited my needs I'd have no worries going with one.

My major negative is that many (if not most) of the modern multis have interiors that are horridly plastic. Imagine2Frolic's is one of the nicest I've ever seen but some of the others...blech !!

Chris White's designs have fairly nice interiors...this is the interior of one of his Hammerhead 34 trimarans.

I'd think also that one of the multis biggest drawbacks is size. It seem from what I read that anything much under mid to late thirties (feet) is not all that desirable. A forty foot cat for two people is an awful lot of boat, a large part of which is simply taken up by a plethora of berths which you cannot use for storage due to the need to keep weight out of the bow. Any comments of that ?

Yes, the problem of weight and all that stowage space is a common one. Having the space tempts one into filling it...causing the boat to be seriously overloaded. Restraint is key to keeping the boat light.

Specifically to you Dog......ignore the fact you own a tri......if money was no issue....Cat or Tri ? I am talking live aboard cruising here...not for a weekender, not for a marina bound floating condo.

I'd probably go for a Chris White designed Atlantic 42 catamaran. Its a beautiful boat with lots of space and moves like a bat out of hell. The pilothouse design gives a very sheltered interior helm position, and the cockpit, located just aft of the mast, gives a very secure location to operate the boat from, even in heavy conditions.

If I didn't want such a large boat, I'd probably go with the Hammerhead 34, which is designed to be foldable for trailering, primarily to allow simplified winter storage.

Generally.....why don't multis have gimballed stoves ? I realise that they don't heel like a mono but even so I would have thought that on any small craft a gimballed stove would still be a good idea. Thoughts ?

They really don't require it from what I've seen.

Last but not least there is also a distressing tendency for cruising cats to have curved settees in the saloon. Useless horrid damn things they are. OK so when you are tied up to the dock they might be tolerable but I cannot for the life of me understand how anyone can get seriously comfortable on a curved settee. Maybe it is just me but I like to to be able to lie down not sit on a boat other than when eating. I may be bent but I am not curved.

The multihulls I like don't have a curved settee...not a one. For instance, the Gemini 105Mc has a U-shaped settee and it happens to be my favorite spot to sleep aboard one, since it allows me to keep an eye on what's going on in the cockpit on night watches.

 

[JohnRPollard]

Dog and I have a shared affliction for those Chris White Designs, especially the Atlantic series. I find them almost bewitching. I much prefer the forward cockpit design, too.

If I ever switched over, and could afford it, I'd be looking for a Chris White designed cat. My current favorite is the A48, which is the smallest one to offer the aft deck (last I checked).

 

[sailingdog]

It is, but the A48 is just too big. 26.25' wide... Not too many travelifts can handle that.

Dog and I have a shared affliction for those Chris White Designs, especially the Atlantic series. I find them almost bewitching. I much prefer the forward cockpit design, too.

If I ever switched over, and could afford it, I'd be looking for a Chris White designed cat. My current favorite is the A48, which is the smallest one to offer the aft deck (last I checked).

 

[TSOJOURNER]

I have one questions regarding sails. Since I don't think it's enough to start a new thread and may give answer to multihull problems I decided to just post here.

Is there a difference in wind force when a sail is loose and has more 'volume' compared to a straight one, but with same cross area?

 

[tweitz]

On catamarans. There is an interesting article in Soundings about the USCG finding a number of rig failures on registered passenger carrying catamarans and ordering extra inspections. The speculation is that most of the cats in question are in warm climates, like Hawaii, get a lot of year round use and rarely have the mast dropped for inspection of the standing rigging. The part that was nost interesting to me is that the CG thought one issue is that on monohulls the heeling of the boat will ease the stress on the standing rigging, whereas multihulls are so stiff that the stresses are higher. It seems like a problem as much of maintenance as design and curable by building heavy enough rigging and inspection, but I never would have thought about requiring stronger rigging in cats before I read the article.