Fast Cat for cargo carrying and research input needed

I am in the VERY preliminary stages of a venture using only renewable power sources across great patches of the Pacific. I am not a boat designer so I need some help in figuring out what we will need to pull this off.

Design requirements:
Accommodations for 8+
12,000 pound payload (predominantly 55 gallon drums)
heavy lift davits (1000 pound+)
8 foot x 12 foot aft on deck cargo space (or if this is not feasible to put this much weight on the back of the boat forward storage with davits to lift into cargo space)
shallow water capable (i.e. dagger boards)
as high performance as possible to help outrun weather
Foiling? Possibly?
all renewable power (torqueedo or whatever alternative power)
of course huge sea and storm safe (Well as safe as is possible anyway!)

Other considerations:
I am fond of the Gunboat style of central helm and sail control systems.
dive compressors and other research equipment will be aboard
Boat will also be used at festivals and races to raise awareness for the cause and to give excursion cruises to donors an the like so comfort, looks, and race boat speed when unladen are also important

So, how big will this thing need to be to carry the weight and whom ought I approach about this project to design and build such a beast?

 

Concepts – Harryproa http://harryproa.com/?cat=51 ... New cargo proa, showing 10 tons capacity

 

Hopefully in before the orcs.

First off, are you sure about that cargo capacity? 12000 lb of 55 gallon drums is only about three pallets worth, four pallets if they're filled with something less dense than water.

That said, I think I'm your kind of crazy. I love the idea a medium sized cat for cargo. I'm actually in the process of building the forms for a little concrete catamaran as a proof of concept for something larger. My wife and I are also going to take a sailing trip in the Caribbean (I'm hoping to get her hooked, but we'll see...).

My personal preference is to Stow cargo in the hulls rather than on deck because having the weight down low it is good for sailing, and having stuff on deck is generally less good.

I'm also in favor of long skinny cats for better stability in ocean swell, and then sizing the canvas to the righting moment.

Richard Woods haunts the forums and has the design chops for what you're doing, so it might be worth taking a look at one of his designs to see what the payload would be.

Catamarans tend to have much more space available than weight, so you could trim down a living quarters on a bigger cat and still be very very comfortable, but having something big enough to take the kind of payload you're talking about would require a bit more digging.

 

Wharrams islander 65 has a 10 ton cargo capacity:

Islander 65, Vaka Motu | James Wharram Designs https://wharram.com/site/professional-designs/islander65

 

Thats a useful looking craft that Rob has designed there.

10 tonnes of cargo and 25 people is a great effort for a multihull

 

Thanks Jorge and R Watson.

A cat is a poor choice for a cargo carrier as it must be engineered to carry it's full load. ie, the rig and the beams have to be engineered to handle the fully loaded boat. Consequently, they are heavier than they need to be the rest of the time. A proa, on the other hand, carries the load in the lee hull, where it has no influence on the righting moment, and hence the rig and beam weights. This makes a significant dfference to the overall weight of the boat, it's cost, performance and it's handling. See below for some examples.

The version shown carries 25 passenger on shortish routes. We have drawn a similar one for adventure cruising for 17 people for 2 weeks at a time for a client in Singapore. Accommodation for 8 people would not be difficult.
It has 10 ton/22,500 lb payload as well as the passengers.
55 gallon/200 litre drums are easy freight in terms of handling and stowage on the boat. On shore, not so much unless there are forklifts and trucks. Our research showed smaller containers were preferred by remote communities. Reducing the payload would allow a narrower, lower lee hull and smaller rig, which would be cheaper. I would not recommend going much shorter as length is easy speed, good seakeeping and low cost.

The latest version of the cargo/ferry has been put through the design spiral a couple of times and lost a lot of weight and windage. Unfortunately, I cannot show this until the client says so.

the deck space between the masts is 10' x 20'. The booms and the masts are used as a crane. The main halyard winch has an electric handle, so lifting and lowering is easy. Additional space could be added outside the beams, but unless your loads are large and light, would not be needed.

The cargo ferry draws 500 mm/20" fully loaded, 200mm/8" empty. As the rudders are side mounted, it can be steered in this depth of water.
Daggerboards make cats perform, but are easily damaged in a collision or grounding. The harryproa solution is oversized, side mounted rudders at 25% and 75% of the length, which kick up in a collision and can be raised for shallow water, off the wind sailing or in a storm.
Most sail powered cargo boats use the sail as an auxillary. Consequently, they require a large deisel powered motor for light or head winds. The cargo ferry proa is designed to sail upwind, tacking through 90 degrees and to sail at wind speed reaching. Performance when empty will be considerably better than this.

You would need a lot of solar panels to power 12,000 pounds of freight at speed in a strong head wind. Plus, if you need to sail at night, a gen set/fuel or a ton of batteries is required. The best renewable option for a boat is wind. And wind is only feasible if the rig and boat are efficient.
It's unlikely you will get a foiler that will carry those loads, certainly not using renewables. We are backing a design exercise at the Australian Maritime College to check the feasibility of a solar powered foiler for a short route in flat water. With some tweaks to the layout, it flies, but only just. Add a decent payload and utility, and it wouldn't.

The bigger the boat, the safer it is. Unstayed rigs are far safer (and easier to handle) than stayed rigs.
Because the proa shunts, it does not need to maintain the high speeds and close windedness that a cat does if it is to tack without getting in irons. The result is the proa can sail slowly and safely, with miniscule sail up, whereas the cat will be at risk of being overpowered.
Above 24m/80' the boat becomes a ship and the survey, equipment, crew and operating requirements become onerous.

It is a good system if you can see the sails, the 4 corners of the boat and all around the horizon, the skipper can communicate with passengers and crew and move easily from inside to out, with the sheets reachable in both positions. A headsail or mast blocking visibility directly ahead is not safe.

The cargo/ferry does this. It is unique, (with an obvious Pacific heritage), so attracts attention, is faster than anything except the dedicated race multis when empty and has plenty of deck space for the guests who will be in no danger under sail. There is plenty of room for dive gear.

The cargo/ferry is designed to be built by local, unskilled labour under knowledgable supervision, which we supply. The machinery required is neglible. The first one has been costed at $AUS300,000/$US225,000 ready to operate. Email me at harryproa@gmail.com and I will send you some more recent drawings and information and we can discuss what is required to make it precisely fit your requirements.

rob

 

Thank you all for your very useful replies.

So, yes the cargo needs to be carried on deck unless a dedicated externally ventilated cargo hold is employed as the plan is for the cargo to be hazardous, which I really don't want inside the boat for obvious reasons (Drum breaks open in a storm and kills us all!) Also, there are no containers larger than drum for dangerous goods other than cubic yard boxes, which will not work at all, as they are cardboard, which would not take outside exposure, and the plastic boxes are very expensive compared to drums. So, ninty-nine percent of cargo would be 55-gallon or smaller drums

The capacity is based around the capacity of a medium small flatbed truck (5 tons) drums are rated for roughly 500 pounds each and a lot of the cargo is typically much lighter than water. The 12,000 pound mark is just a rough target, 10,000 of cargo with another ton margin just for safety. All the cargo I would carry would be weighed and manifested so accurate weight control is assured. I was kind of thinking along the lines of the Mconagy MC50 McConaghy Boats https://www.mcconaghyboats.com/mc50cat with the lifting swim platform as a cargo deck. My worry is concentrating all the weight at the polar end of the boat like that. Truly, probably not the best solution.

The route is to be the South Pacific island groups and back to Hawaii, so a lot of big ocean passages. (Possibly to New Zealand or Australia but all my sponsor/vendors are USA based currently) Massive quantities of speed are obviously desirable for the distances involved.

The plan yes is to have a generator, I would like not to, but its really quite necessary, especially during research vessel operations. The system in mind currently can be seen on the gunboat 60 "moonwave" Sailing Catamaran for Charter - Gunboat 60 - MOONWAVE http://www.moonwave.com/ ideally the auxiliary is used only for maneuvering, if we are becalmed.... well we do what sailors of the past did, we wait. And I think it should go without saying that possibility of foiling is only when under sail.

Lastly, the boat is going to be used as a publicity boat to attract sponsors so fast, and sexy are also high priorities. Think, racing the Cariibean 600. or the ARC, or Transpac, entertaining guests and sponsors. Like "Turn the tide on plastics" VOR boat, but I want this to also be working boat, not just a race boat. If this thing works out, subsequent boats probably be different, more pure work boat, not flash and race boat, but this one is to attract attention.

That said, Rob, the build price for that ferry/islander proa is very attractive! I am really quite interested in the concept, but like I said, cargo must be on the deck, cannot have it enclosed. You said faster than all but a pure race multi, what are you thinking for speed when unladen?

Again thank you all so much for your replies!!!

I looked at the Wharram design when I did a search for this topic, looks like 65 feet is a good estimate of size for the weight to be carried. One idea is that I put the cargo in the sail handling area near the mast. (i.e. gunboat 66(can you tell I have a small kind obsession with gunboats, sad what happened)) that would keep the weight to the center of the boat at least, and just have davit mounts at the dagger board pockets.

Thanks again, please keep the ideas flowing. I love this stuff, but I've never designed and built a boat myself, so I need all the help I can get!

 

What RD said - A proa, on the other hand, carries the load in the lee hull - is a key comment or else you fall into the design spiral. The heavier a boat, the bigger stronger beams, masts everything needs to be sized up. Maybe not a problem if you have the budget ...

 

If publicity and sailing performance are truly your ambitions, you might like to consider changing out sails for the more efficient and higher performing Rotors.
These are being adopted as solution for an increasing number of commercial cargo ships, and it would scale down to a 60ft proa relatively easily, driven by electric motors.

You would get a few eyebrows raised with these babies.


Check out :-

Everything Old is new again - Flettner Rotor Ship is launched https://www.boatdesign.net/threads/everything-old-is-new-again-flettner-rotor-ship-is-launched.24081/page-32#post-823737

 

Again, since

The cargo hold can/will/should be sealed by bulkheads from the rest of the boat anyway, and having it on deck, you're potentially leaking all over the place. If you do have a leak. A vented and sealed compartment is a relatively trivial addition, especially at the volume you're talking about (16 x 8 hold in each hull perhaps).

As far as auxiliary power goes: Solar panels combined with batteries should be easily enough for your needs. Lithium ion and solar has become really cheap (relatively speaking), and with a 65 ft cat you're looking at several kW of capacity. Not enough to plane, but easily enough to navigate harbors, and probably give you a little boost on the ocean. It also has the benefit of providing power for various amenities while under way, being quiet and odor free and not requiring fuel.

Which brings me to my next point: I would be thinking much more about operating costs than initial purchase cost. Hull material, sail material and sheet material : be thinking about the things that will have to be replaced due to sun and seawater exposure.

My personal feeling is that an ultra-high performance concrete would make an excellent hull material for your purposes: It's able to be made incredibly resilient (pva fibers and water reducers, fiberglass or basalt reinforcing armature), relatively light weight (on par with plywood, normal wood or steel) but perhaps most importantly for your purposes immune to sun and seawater. Even fiberglass is going to need painting to resist UV damage.

As far as 'fast' goes: I think you might want to start looking at goals for speed, perhaps as a percentage of windspeed. Your gunboats (etc.) are deriving their speed from the use of ultra-lightweight materials ($$) and being canvassed to the moon (big sail means you're reefing in strong winds). When you look at boats designed for long range voyaging, you see a lot more multi-sail arrangements; Ketches, schooners, and cutter rigs become more common because they give more sail area in more manageable sizes.

 

Here's the latest thread about concrete as a hull material:

Ok everyone, it's that time of the year again: time to talk about concrete https://www.boatdesign.net/threads/ok-everyone-its-that-time-of-the-year-again-time-to-talk-about-concrete.59200/

 

your catamaran could have 4 sails for more stability, but minus the fly-bridge.

 

Truly, indeed. 5 tonnes on the back of a cat smaller than a superyacht would be a disaster.
Deck storage on the cargo ferry is not a problem, the latest iteration has it. Drums are 600mm/24" diameter. 12 of them fit easily. Stack them, and you could fit twice as many, subject to the weight not exceeding the design weight. Equally, containing it in the hull if it was to leak is simple (the living and sailing is all done from the other hull) and better environmentally than losing it into the ocean.

Speed comes from low weight, sail area and length. Performance, which includes upwind ability, requires decent leeway resistors and minimal air and water resistance. South Pacific/Hawaii is not an easy voyage, wind wise. Nor is Hawaii to the mainland. The boat should perform well upwind and in the squally doldrums.

Diesel/electric is an option if money is not a problem, but will harm your green credentials if these are important for funding etc. Props on shafts or saildrives limit your shallow draft and drying out options. Folding props are required for sailing performance, but are not efficient for motoring. Making the props liftable adds complexity and cost.
The cargo ferry has 37 sqm of solar panels and sufficient batteries for docking at night or in the rain. No fuel is required and on sunny days with no wind, you motor at 6 knots. When sailing or drying out, the prop is clear of the water. It is also easily reached for clearing plastic bags, ropes, etc.

The laminate in that price is for survey purposes. Because the boat is novel and surveyors cautious, it is heavier than it would be for a private vessel. If your fitout was minimal and you removed the extraneous stuff for racing, the cargo ferry, built from foam and glass would be racing at about 6 tons. Sail area is 220 sq m/ 2365 sq ' This gives a Bruce number of 2.1. The Bruce number is a power to weight ratio. The square root of the sail area in sq' divided by the cube root of the displacement in pounds. Higher is faster. Compare it with whatever boats you are contemplating racing against. ie, Gunboat 66 weighs 18 tons/tonnes and has upwind sail area 2,232 sq ft / 207 sq m, downwind sail area 4,667 sq ft / 433 sq m, so Bruce numbers of 1.4 and 2. It is also 14'/18% shorter. The Gunboat mast is 28m off the water, the harryproa 24m. Build the harryproa from carbon, which is nowhere near as expensive as the Gunboat advertising would have you believe, and the difference is greater. Build the Gunboat to take an extra 5 tons of load (see my original post re over building cats for max loads) and it would be greater again. If you really wanted to race, add 4m sleeved topmasts to the harry and an extra panel to the bottom of the sails and you would give the Ultime tris a run for their money.

The empty Wharram weighs 9.5t with 1240 sq' of sail upwind and down. Bruce number 1.3. It would have a bigger payload than the Gunboat, be more suitable for shallow areas and has a better deck layout for freight. It also has an easier to handle and maintain rig, although neither of them is as easy as the harryproa's. Without dagger boards, the Wharram will not sail upwind well.

Dsigned,
Concrete has some appeal. What were the dimensions and weight of your second panel mentioned on the other thread? Did you subject it to any testing?

You are correct about running costs being important. The harryproa solution is to minise the things that need replacing. 2 winches, sails, halyards and sheets, plus a couple of turning blocks and 6:1 blocks and tackles. Masts that do not need tuning or inspecting, have no sail tracks and cars to break and no standing rigging to check, worry about and replace. Simple steering, no daggerboards, no hydraulics.
You are also correct about large sail areas needing regular reefing. Not so much about multiple sails being the best way to achieve this. A better solution is unstayed rigs where the sails can be raised, lowered, reefed and completely depowered on any point of sail, regardless of wind strength and direction. In a squall, you dump the sheet and the boat quietly drifts. You can get a cuppa and wait for the squall to pass or sheet on just enough to give you the power you want. If you decide to reef, you dump the sheets , the boat drifts and you reef at leisure. This beats wrestling with flogging headsails on a wet foredeck. 2 sails which are up all the time are more cost effective than multiple sails which are only used in specific situations (down wind, light or heavy breezes).

RWatson,
I have it on pretty good authority that a major Pacific shipping company is about to fit Flettner rotors to 3 of their inter island traders. It will be interesting to see the results. While I can see why they are used on ships (less deck area, no trimming), I'm not so sure they would be much good on a performance oriented, load carrying small(ish) boat.

 

It's hard to imagine, but the results would be spectacular. The number of "slow" cargo carrying freighters is growing fast. Check out the last few pages of the links I posted. You have to remember, that the cross section of each rotor has to be multiplied by 7, to achieve the equivalent performance from conventional sail. Add to that the "dial it in" control of rotation,( which is equivalent to reefing ), is a huge saving in handling problems.

Here is a video of a lightweight multihull in action

 

No "second" panel yet. I made a few more panels (one with perlite, one with more vermiculite, one with just mortar and burlap), but nothing "better" than the one described. However, I did finally get my hands on some pva fiber, I bought an old blender from a thrift shop to grind some glass with. I still need to figure out how to sift it, but I'm probably pretty close to the next panel.

As far as testing goes, I haven't had time to think about how I'm going to rig up a test. I teach math and have three little monkeys at home, so concrete testing has to fight for time against those, which is a fight it usually loses...

I think the matter of which sail pattern is "best" for being shorthanded, etc is a matter on which rational people can disagree. I do agree about the unstayed rig though. The freedom 44 (fully battened cat ketch) and the junk rigs are both sail plans I like. There's a video floating around YouTube of one of the freedoms flying ONE sail, reefed and blowing past a similar size boat. I also like the idea of having less stuff on deck to get tangled in, etc.

I'm not sure how I feel about headsails. Honestly I haven't sailed long distance at all, so I suspect I'd have to do some voyaging with different systems to have any kind of opinion on what kind of system is "ideal"