Catamaran

[Carols]

Has anyone got first hand on experience of a catamaras stability as aposed to a planing hulled boat?

 

[Nautorius]

Has anyone got first hand on experience of a catamaras stability as aposed to a planing hulled boat?

Are you talking about a planning Catamaran or a Displacement? Any idea on LOA and Beam? We need more info,

Paul

 

[Carols]

How stable are catamaras

Thanks paul, it's semi displacement 6.6 meters beam and 12 meters lenth

 

[chrisbarrett]

Cats

Are we talking about a Lagoon Power or similar.

 

[Carols]

Cats

Yes

 

[Nautibusiness]

Have briefly helmed many cats (commercial / fishing charter style) and also delivered a displacement (wave piercing) 13m cat from Padstow to far north Norway.

I love them, but not everyones cup of tea.

Amazing efficiency, incredibly laterally stable, silky smooth ride (anything other than a very big head sea).

They can be a bit twitchy in a following sea due to two reasons.
1) The big fat back end can get pushed around if going slower than the sea
2) On the displacement and semi displacement cats, the bows have relatively little buoyancy and can dive into a wave on the downward run. This can cause them to try and steer from the bow.

The cat I delivered was ugly as sin, but built for a purpose and amazingly spacious.
She was a 13m Powerglide Cat, built for filming and fishing charter. She was fitted with 2 x Iveco 285's which gave a top speed of 24.5 knots, but she cruised almost anywhere in anything at 21 knots and returned a total fuel consumption of 3 litres per nm.

http://www.troms-explorer.com

I would have one over a mono hull anyday, but it's very hard to convince the UK boaters of the same. We are a little stuck in our ways.

Tom

 

[oldsaltoz]

Has anyone got first hand on experience of a catamaras stability as aposed to a planing hulled boat?

.
Well, stability at rest is a no brainer, a cat covers a wider area so is more stable.

Having said that, it is very important that you have good clearance between the hulls to avoid slamming in larger waves going to windward. 0.75 m would a minimum, more is better, a lot more is best.

As stated above they can tend to wander in a following sea, a bit more than mono in some conditions like short sharp waves and the hull moving slower than the waves.

However be advised that the motion of a cat can be very different to mono underfoot; the problem being that the deck may rise a couple of inches and cause your foot to land shorter or further down than you expected, causing a slight trip like action, we have a saying on board when this happens, 'who pushed me', you end up lifting you feet a bit higher when you get your sea legs though.

The big change you will notice in very slow and small angle change when under way or a rest in waves.

So in summary, generally more stable.

Avagoodweekend......

 

[Carols]

Cats

Great thanks for your help that puts my mind at rest cause Im fed up of slamming about in our sports cruiser
I believe every marina will want to charge us double for moorings is this the case?

 

[PaulGooch]

Great thanks for your help that puts my mind at rest cause Im fed up of slamming about in our sports cruiser
I believe every marina will want to charge us double for moorings is this the case?

Not always Carol. Some charge double, some charge an extra 50%. Some even charge the same. At any given marina it may also be dependent upon the beam. I've also seen some that charge the same as a mono hull, if it will fit in the same berth.

 

[oldsaltoz]

Not always Carol. Some charge double, some charge an extra 50%. Some even charge the same. At any given marina it may also be dependent upon the beam. I've also seen some that charge the same as a mono hull, if it will fit in the same berth.

.
You can often pay the same as a mono if tied up the end 'T' of the pontoons or a side on berth.

 

[Garold]

Great thanks for your help that puts my mind at rest cause Im fed up of slamming about in our sports cruiser
I believe every marina will want to charge us double for moorings is this the case?

When we went to 2 hulls we did notice a change in our yachting costs.

If you are required to pay more for a berth then it's best just to grin and bear it because it's probably fair. With a cat, one probably has the accom of a yacht 30 to 50% longer.

However, after running a cat for 2 years on the Solent and Channel, our berthing charges varied enormously. Roughly half of marinas charged extra for the extra hull but others were just fine with it. We did make sure that our permanent berth was one that had no premium for cats. So, it was just the occassional shock when touring.

Another important consideration is that in a cat one tends to feel a bit more willing to sit at anchor, or on a swinging mooring because there is less rolling and also one has a bit more deck space to stretch legs etc. This changed our cruising quite substantially and we only visit marinas if there were no other options.

But bear in mind that this is the view of a raggie so not sure if it's the same in a mobo cat.

Cheers

 

[Davy_S]

To attempt to reply to the Nautibusiness thread, I remember a long time ago, a charter fishing boat out from Plymouth (I have fished from most) a boat called Artilleryman, Geordie Dixon, bought a cat, first reports suggested that it burried its bows in a following sea. I seem to remember that the forward hulls were extended giving aditional bouyancy, after this modification the ride quality was increased dramaticaly, it was far superior to the mono hull type operating between Plymouth and Guernsey. Dont know if anyone from this area remembers this. Round about the time that Boa Pescador, (Steve Barrat) and Satrat (Lochin33), June Lippet, Buster to name a few, operated from Plymouth

 

[Nautibusiness]

To attempt to reply to the Nautibusiness thread, I remember a long time ago, a charter fishing boat out from Plymouth (I have fished from most) a boat called Artilleryman, Geordie Dixon, bought a cat, first reports suggested that it burried its bows in a following sea. I seem to remember that the forward hulls were extended giving aditional bouyancy, after this modification the ride quality was increased dramaticaly, it was far superior to the mono hull type operating between Plymouth and Guernsey. Dont know if anyone from this area remembers this. Round about the time that Boa Pescador, (Steve Barrat) and Satrat (Lochin33), June Lippet, Buster to name a few, operated from Plymouth

I know Geordie D and Artilleryman, but perhaps the one I remember was the mono as I don't remember her as a cat.
What I think you are describing is the early Blythe Catamaran.
The originals were verging on planing hulls but with almost zero bow buoyancy and they did have a rather nasty ride.
Pretty soon they all came with small, but extremely effective bulbous bows and yes, they handled properly after that.

The Blythes are rather cheap compared with the modern planing versions from South Boat and the displacement and semi displacements from Powerglide and BWSeacats for example.
Blythes are still popular, but the other manufacturers are overtaking them (very fast) in ride, handling, technology etc.

 

[hobiecat]

Wide catamaran platforms have great stability - enough to support a sailing rig. Taking the sails and rig off means you have immense stability and a nice working platform to fish, live etc. However, wide platforms are generally not so fuel efficient at higher speeds. They generally need more surface area in the water to suppport the extra weight and it is surface area that is the important determining factor in top speed. Beam to length ratio of sailing cats can be as much as 2:1 and they use the same moulds to build motor catamarans

Fast motor catamarans are more efficient if they are narrower.(displacement speeds say up to 25 knots) and length:beam ratios say 3:1. They can benefit from airflow being squeezed between the hulls to create an air cushion for a comfortable ride.