Looking for a long range expedition aluminum power catamaran design

[Eurosnob]

Since you initially said you're not interested in sailing(?) and if you're not absolutely set on the catamaran layout then perhaps some inspiration can be taken from the new(ish) style of stabilised monohull workboats that are being used for oil rig & wind farm crew transfers?

Plenty of workspace in these designs!

You could even go SWATH!

 

[comfisherman]

Any videos of that going through some rough weather. Pretty radical design...

 

[Eurosnob]

Any videos of that going through some rough weather. Pretty radical design...

Not of rough weather. Company promo's & on-site videos with calms seas & no wind only it seems.

I don't know if any of the bottom render have been made.

 

[icefrontiers]

If you want to stick to a motor boat and are willing to put some effort into a remodelling project, I would look into getting a fishing boat. The fishing industry is in crisis in many locations. There are probably boats available at a fire sale price. It will get you the range and volume you need. Not sure about the total cost of the project, but I suspect you'd get closer to your specs than trying to repurpose a boat designed for the charter market.
Another option is to buy an expedition sailboat. They tend to have big engines, large tanks, and sailing can be learned. They also have space. They are usually fairly custom and you have to look globally. I recently purchased one in New Zealand and I am in the process of sailing it back to Alaska and British Columbia. We sailed when we could, but we will probably have spent close to $7,000 in diesel by the time we get to Dutch Harbor. You can find more information about the boat here:
- Fuel Management Offshore: What Sailors Get Wrong https://icefrontiers.com/fuel-management-offshore/
- Meet Rosemary: a Legacy Expedition Boat From French Lineage https://icefrontiers.com/meet-rosemary/
-

I hope this helps.

 

[gonzo]

We need to modernize the motorsailer.

I think the modern motorsailer already exists. The so called sailboats with auxiliary motors cruise at the same speed motoring as sailing. That is the definition of a motorsailer: a vessel that operates at the same speed under both types of power.

 

[TANSL]

From ChatGPT : "A motor sailer (or motorsailer) is a boat that is designed to operate efficiently under both sail and engine, giving each propulsion system a significant role."
Nothing about "the same speed"

 

[MikeJohns]

From ChatGPT : "A motor sailer (or motorsailer) is a boat that is designed to operate efficiently under both sail and engine, giving each propulsion system a significant role."
Nothing about "the same speed"

Agree but ChatGPT is not a reliable definitive source IMO !
It also misses the importance of declaring the ratio . If there's no ratio along with the designation Motor-Sailor then it's more a description of looks rather than capability.
For example:
Most 50/50 motor-sailor designations when reasonably rigged and with the 'power to carry a decent spread of sail' in anything over force 5 will have their best speed under sail. That's just because of the constraints of designing the propulsion system around a sensible operating point. But the same dosen't hold with a 70/30 motorsailor which is designed to use sails to reduce fuel consumption and usually limps along under sail and lacks the stability to 'carry sail. But both designations are valid as motor-sailors.

 

[montero]

I was planning a trailerable power cat and recently I've been considering sails for it.

I don't see any reason why sail propulsion would cause instability.

 

[TANSL]

I don't see any reason why sail propulsion would cause instability.

Perhaps you haven't considered why sailing ships heel when sailing upwind. They do, and quite significantly, which is why they need to be fitted with large keels and ballast placed as low as possible. The mast and rigging alone, being heavy and having high centers of gravity, reduce stability.

 

[TANSL]

Agree but ChatGPT is not a reliable definitive source IMO !
It also misses the importance of declaring the ratio . If there's no ratio along with the designation Motor-Sailor then it's more a description of looks rather than capability.
For example:
Most 50/50 motor-sailor designations when reasonably rigged and with the 'power to carry a decent spread of sail' in anything over force 5 will have their best speed under sail. That's just because of the constraints of designing the propulsion system around a sensible operating point. But the same dosen't hold with a 70/30 motorsailor which is designed to use sails to reduce fuel consumption and usually limps along under sail and lacks the stability to 'carry sail. But both designations are valid as motor-sailors.

I'm not a fan of ChatGPT, but on this occasion, he provided me with a simple and accurate definition. Of course, there are other, more technical definitions that use formulas to delimit the concept. But none of them mention equal or similar speeds.
Following your reasoning, and applying the formulas I mentioned, one could have a motorboat with a sail that wouldn't be considered a motor-sailer.

 

[montero]

Perhaps you haven't considered why sailing ships heel when sailing upwind. They do, and quite significantly, which is why they need to be fitted with large keels and ballast placed as low as possible. The mast and rigging alone, being heavy and having high centers of gravity, reduce stability.

There is my thread on multis . Cat bulkhead design . Beam is my antidote to heel. Freestanding light masts also .

 

[TANSL]

Yes, yes, that's clear, but you'll agree with me that the mast, rigging, and sails are elements that produce instability.

 

[montero]

I agree. That's why I'm thinking about low and foldable masts. Or non-vertical masts. Or kites.

 

[brian eiland]

I looked back at an old design of mine from 25 years ago. The basis of the idea was to develop a simple, efficient cruising rig ,which might be handled by as few as one person. Preferably this crewman did not have to leave the central cockpit area and/or over-exert himself in handling the sails. The rig needed to have good balance, in a variety of sail configurations which might be utilized in sailing the great variety of ocean and wind conditions it might encounter. Without going into details, this rig accomplished all those objectives, plus all of the sails simply roll up like old style window shades around their forward support wires (forestays). Very simply for non-sailors.

Full Sail Click for Larger View​	Trolling Sail Click for Larger View​

Gamefishing under sail? A great majority of the time spent actually fishing is done at trolling speeds (particularly so with the more recent popularity of flyfishing and light-tackle/stand-up styles). This catamaran can reach those trolling speeds under sail alone, in a silent, effortless, stable manner; and without having to use multiple sails. The single central sail (mainstaysail) is all that's needed to reach trolling speeds, and it can be rolled and stowed in 30 seconds or less, while the engines are engaged for exceptional maneuvering while landing the fish for tagging. I'm well aware that once a large gamefish is hooked, the vessel must get rid of all sail quickly, with minimum effort, and get under power. This unique vessel accomplishes that.​

And how about the rigging of the sail plan interfering with the fishing? Not much - look at perspective view. The wishbone boom swings up, to stow totally out of the way while trolling. The entire aft deck is clean except for the two backstays which broadly 'Y' out to either transom. Two short pole outriggers can be swung out from their stowed position up along side these backstays. Its possible that this upside down 'V' formed by the backstays could be rigged with additional trolling clip attachments. The actual configuration of the fishing cockpit area may be altered to suit the owner. Mr. Peter Wright, a very well known name in offshore fishing around the world, has indicated that he would be very pleased to help with the final configuration.