Multihull Structure Thoughts

Fallguy, your contributions are very welcome as are others who wish to share information. Shared knowledge helps us all. Coastal Ogre I will be doing the Stealth cats soon. Guzzi 3 I will try and get to an additional "length" index so to help people locate boats by length easier.

 

This is the correct link:
https://catamaranguru.com/wp-content/uploads/2020/03/catamaran_bridgedeck_clearance.pdf

 

The following will be in 2 parts. First will be about a 34 foot aluminium power catamaran, the second part will be about the hybrid electric power option available for this cat. The cat is the Herley 34, a 34 x 15.4 foot cruising power catamaran designed by Roger Hill that displaces 16,120 lbs loaded. The hull length to beam is about 13 to 1. The cat draws 2.5 foot. The basic boat is offered with twin Volvo D2-75F as the propulsion unit through to shaft drive. The drive shafts lead to propellors are recessed in tunnels in the stern of the hulls. Alternative options are outboard power or a diesel electric power option we will discuss tomorrow. The fuel tankage is 680 litres. Depending on the power options the cat can do up to 21 knots but the 34 normal cruising speed is between 8 to 14 knots.

The catamaran configuration provides space for two double cabins in the forward area, each with a generous size double bed. A toilet on the port side and separate shower to starboard provide facilities for extended cruising. The saloon area has a steering engine control area forward for internal steering control. The saloon area also a compact galley with a sink, fridge and cooker unit with a double hob and oven. Hob and oven are a Wallas diesel combo unit, so neither petrol nor LPG are carried on the boat – it runs on the same diesel that provides for the extended range. Opposite the galley is a triangular dining table and L-shaped couch that faces the wide-opening rear saloon doors. And it is out through those doors that most time will be spent. An island console in the large cockpit provides a bait-board, live-bait well with tuna tubes, sink, rubbish bin, storage lockers and saltwater washdown hose. The floor’s covered in SeaDek for a comfortable barefoot experience and easy cleaning. The boarding platform is the full width of the boat, with the running gear tucked well out of the way of both swimmers and fishing gear.

The Herley 34 shell structure is all aluminium using 5mm plate on the hulls and 4mm on the topsides. There are the usual stringers and frames for rigidity and strength. The semi-displacement hull form has been specifically designed to create the minimal underwater drag. The internal furniture fitout structure is plywood with various finishing materials such as tan leather-look vinyl trim, walnut cabinetry and pure-white headliners.

The tests of the boat talk about its excellent control and good seakeeping qualities at 8 to 10 knots cruising speeds.

The jpegs give the idea of the boat and the build. Tomorrow we will focus on the motive power.

 

The Herley 34 does look amazing - a really nice ally power cat.
I downloaded the brochure for it - to do so I had to submit my name and email address (so I guess they will be contacting me soon if they do not hear from me) - but in the brochure they mention the basic price for the boat - NZ$ 950,000.
That is approx US$ 685,000.....
Herley Boats 3400 - Download your Free Brochure https://powercat.herleyboats.com/download
A lot of money for sure for a 34' boat, although I suppose that being a cat she is almost two boats.

 

Admittedly, some good features, but I plan to keep my boat at my home, so I am glad to be able to pull engines out of the water.

I did my level best to try to reduce fuels, but diesel outboards are too expensive. Inside the boat, a diesel heating system led to the most likey stovetop to be a diesel, but diesel stovetops are basically big griddles and they get hot. Moving to Texas, the last thing I want was a hotplate inside the boat just to heat some coffee, so also have propane now onboard.

The better way to go may have been electric, but I only have practical room for four batteries and 800w solar or less and I dislike a noisy generator with some passion.

The reverse rake of the Herley I cannot get used to. She has much more accomodation than the demountable Skoota, but she is also really heavy. I wonder how she'll do on fuel economy and range. The Skoota is 128 gallons versus her 180 gallons. Performance(speed) expectations are very similar. I have twin 90hp vmax Yamahas on the back.

I should add, the fixed version of the Skoota 32 is a very formidable opponent to this boat.

 

The Herley 34 is an aluminum power cruising cat that has a diesel electric option compared to the twin Volvo D2-75F diesel engines. The diesel engines will give a range of 1300 miles, the diesel electric hybrid engine option will give a range of up to 2500 miles with the same 680 litre fuel tanks. Great! But the cost of the basic cat is $900,000 NZ, if you want the diesel electric options costs $1.25 million NZ. Yes, you read that correctly the hybrid/electric version costs over $300,000 more.

All you need to do is add liquid cooled lithium iron batteries, solar panels on the roof, some very sophisticated controller units, a powerful diesel generator, some very good wiring and 2 large electric motors. All expensive and in need of some very good waterproofing to work well in a marine environment. Parts of the following are from BoatingNZ and Powerboating magazines.

The Herley Electric Powercat 3400 is powered by a 60 kWh Li-Ion battery bank which runs two 100kW electric motors, driving the power through shafts, with the propellers set into tunnels of the displacement hull. A planetary gearbox reduction @ 3:1 produces a maximum shaft rpm of 1500. The battery bank has a nominal 350v, with a 176Ah capacity, 61.6kWh and weighs 600 kg. Liquid-cooled (50/50 water/glycol liquid cooling), they have an integrated BMS (Battery management system) plus safety features such as a Redundant BMS, Thermal propagation, Protection between individual cells, rupture disc with venting exhaust and DNV-GL Class approval. It also boasts a 120kW variable speed generator. This generator provides a Hybrid range extension feature and redundant power in the case of Battery Management alarm. The hybrid control and operating system has been developed in house and is designed in a scalable format to accommodate future builds of all sizes.

The brushless permanent magnet electric motors have a 100kw peak and 60kw continuous output. The engines are liquid-cooled (50/50 water/glycol liquid cooling), with an operating voltage of 350v DC, maximum efficiency of 95% and weighing just 50 kg. The hybrid package also comes with a DSP-controlled inverter with sine wave drive.

The new Herley Electric 3400 uses 1.89kw maximum output solar panels with a charge time of approx. 36 daylight hours. The boat has a shore power connection which will fully charge the battery bank between 1.5hrs and 6 hours, depending on the amperage of the shore supply.

For comparison a Tesla S base has a 60 KW battery (can have a 95 KW) and a 400 volt architecture. Porsche Taycan run 75 to 95 KW batteries and 800 volt architectures. Both cars have regenerative braking and are as complicated in their electric management systems as the cat but cost less than $200,000 in the base models. But there is also a small risk factor. A Tesla road car hit a tree in the USA, it took 4 hours and 30,000 gallons of water to put the battery fire out, as the lithium iron battery kept on reigniting when fire fighters thought it was out.

But what does the fully electric drive mean. Twin 100kW electric motors (peak output 60kW continuous rating) push the efficient hulls to a top speed of 20 knots. The onboard battery bank allows her to run for a couple of hours at a more modest cruising speed. Since the motors can run literally from 1 rpm she is far, far, easier to manoeuvre at slow speed around a marina than most fossil-fuel boats which typically idle at just under 1,000rpm.

The range extender system includes a 120kW diesel permanent-magnet generator, which gives her an estimated cruising range up to 2,500 nautical miles at 8 knots from a modest diesel fuel tank (640 litres). Performance figures so far indicate she can run continuously at 14 knots using just 0.73 litres of diesel per nautical mile, or at 9 knots using 0.5 litres. As the test boat has the smallest possible battery bank size (the batteries could be doubled or even tripled) she can run for up to 36 nautical miles on battery alone, or less at faster speeds.

‘Sport Mode’ lets Herley 34 run on batteries and generator and gives her maximum speed. The cabin roof is covered with 14 high-efficiency solar panels, providing self-charging capacity to power the extensive list of on-board accessories. These include fridge, freezer, hot and cold fresh water, large-screen TV, stereo, navigation electronics and, of course, inset LED lights everywhere including below the waterline.

So, in summary, you get about twice the range running the hybrid system for the same fuel tankage in a very interesting boat that according test reports performs very well as a boat. The jpegs give some idea of the power systems.

 

But she isn't really a bluewater boat is she?

I never understand pushing a range of 2500 miles. At some point, I want to make some long runs if I make 2000 mile runs and Hawaii is so far from California. Maybe someone can explain how 2500 beats 1200 (or where). My boat's range is about 500 miles which is plenty for gulf fishing or Inside Passage, etc. It is a long run to Florida from sw Texas and would be nice to take a shortcut across open sea. So I get the 1000 mile range option. Maybe there are lotsa places 2500 is needed..

 

For vessels crossing the Atlantic from Europe to the Caribbean, there is about 2,800 miles between the Canaries and Barbados in the West Indies, and it is still 2,000 miles if one 'jumps off' from the Cape Verde islands instead (which are approx on the same latitude as us here in Barbados).
So a 2,000+ mile range is useful.

It is easier (in a way) heading eastwards across the North Atlantic - for instance one could go from Newport to Bermuda (about 600 miles), then to the Azores (about 1,900 miles) and then to Portugal (about 800 miles).

 

This discussion might get interesting...

And full disclosure; I'm a big proponent of innovative technologies. But that is an 'eye-watering' option for the hybrid propulsion!
If your going to motor across large expanses, most employ flexible fuel bladders (a.k.a. pillow tanks). Fairly certain you can buy a lot of spare bladders for $300,000 NZD for those times when your making the transit to the Caribbean Seas.

There are many folks who jump seasonally from Florida and do not stop (for various reasons) until St. Thomas. And that (route dependent) is still only ~1100 miles. I guess if you want to be able to motor for 2500: it is a bragging point. As most folks may not wish to be floating non-stop for that length of time. Still maybe some do...

In summary: a.) actual mileage might vary from initially published numbers here, b.) bragging rights do sell boats (just like how they publish mileage on personal light jets), c.) commoners (like me) really don't need this inherent range, d.) still cool stuff tho.

Cheers - Ogre

 

For fallguy, from another web site September 2019 – Blue Nomads https://bluenomads.blog/2019/09/
This site is worth an explore.
"The Silent 55 is a solar-assisted, pure electric or hybrid diesel-electric power catamaran that can passage make at 100nm per day on solar alone – essentially forever (at only 4kn though). Or it can go at 6-8kn combining both solar and diesel (range is uncertain, but with 600L diesel for the genset combined with daylight solar, it should be over 1000nm). So here is a passage maker that can go faster for short distances, or essentially has an infinite solar-powered range at lower speed."
"The Leopard 37, which are delivered to the Caribbean on their own hulls from South Africa even though they have a nominal range of 900nm only. They did passages of over 2500nm at 7kn in the most efficient fuel zone, a single engine at a time, and using extra tankage which make such long passages quite feasible for the few times they are needed. Some may argue that the fuel consumption figures are for calm flat water with no tide and thus theoretical and impractical as far as passage making in concerned: the delivery of the Leopard 37 should put that to rest as they encountered a variety of conditions in the Southern Atlantic including 35kn winds"

 

Moderator. Can you please put the following 2 sheets on the page 1 index area of multihull structure thoughts. If the group thinks it is a better index arrangement I will expand it to all entries on the thread and get rid of the original index pages.

Folks, if you like the new index approach please indicate with a like or comment.

 

Added to first post as well. Thanks.

 

Those are some beautiful awesome boats.

But in my humble novice opinion a sensible long range solar cruiser should be designed more modest. The current designs try to do everything current luxury power catamaran do and, well, succeed - but are way too expensive and the sustainability gains are questionable. Instead compromise more for low power and low speed and compete with an average (monohull) sailboat cruiser.

For example a lightweight 50' 4t slender ILAN type trimaran cruising at 6-8 knots. Less space but enough for a couple living comfortably and the occasional guest, maximum solar panel roof surface for more solar gain at anchor, allowing a smaller cheaper battery plus a cheap off the shelf 5kW generator for backup / winter. This could then be even cheaper and less complex than a motorsailer.

 

How close are we to the cost of a decently capable solar/battery bank installation becoming cheaper than a sailing rig?

 

Possibly 50m² of glass solar is 10kW, 500kg and ~7500€. House battery of 10kWh LiFePO4 is ~4500€. I don't want to derail the thread too much, although this does require some new thoughts on multihull structures