|
Greetings,
we are a young couple considering building a boat as our home after we finish our studies. We have found that Bernd's designs, particularly the KD860, seem to tick many of our boxes in terms of comfort, layout and cost.?
?
There are two questions that arose, which we did not find answered on this forum yet:
?
A) although we are likely to stick to the cheapest propulsion option (assumed diesel outboard) at first, the long-term ideal (we assume) would be a solar-electric drive, using better bulk energy storage than batteries (hydrogen, formic acid, methanol fuel cells... we are chemists, and so open to experimentation here).
? ? ? The question then is: since based on the 'Hull speed / motoring kd 860' thread that boat doesnt do well under power, how hard of a tweak would it be to make the KD860 a better medium-speed (<15kn) motor boat? Or are there any other designs with comparable accomodations, sea worthiness and cost that would be better suited to this role? (I have found the Eco85 powercat threads, no expected specs/material costs/layouts though, and we like the compartmentalisation/layout of the KD860).
?
B) we unfortunately live in the smack middle of Europe- even a trip to the Danube (our only navigable river) is 100+km. It was mentioned in the thread 'weight of hull KD860 - moving' that transporting the hulls and center separately is possible, though not ideal- 100h asssembly, 250h finishing.
? ? ? What is meant by 'finishing' please? Is the boat liveable by that point? How much complication is added by such an approach, and what are the requirements on the place of final assembly in terms of space, equipment etc?
(Ps. I know the default answer is that companies exist that can transport finished cats, but we are on a tight budget, and live in eastern europe where a French business may ask premium. Apart from that, we would like to have a fallback plan.)
|
The cheapest propulsion system, and the most simple is a petrol outboard, one specifically designed a a yacht auxiliary motor. A good example of this is the Yamaha 9.9hp high thrust outboard. This propulsion system is tried and tested and works well. Then have an array of solar panels to provide power for all the other yacht systems such as refrigeration and lighting.
?
Electric propulsion is certainly an option, but will be a lot more expensive, and require a lot of batteries, all of which add undesired weight to a lightweight multihull.
?
The way to make any boat go faster is more horsepower which requires a heavier motor, more fuel used, and more batteries if you go to electric propulsion, and probably a reduction in range if you go electric.
?
Bernd can best comment on whether the KD860 hulls are suitable for higher speed, they probably are. I drive high speed catamaran passenger ferries as an occupation. These ferries are up to 30 meters in length and feature narrow semi displacement hulls. They cut through the water nicely and we operate in the 23 to 28 knot speed range. But it is still takes a lot of horse power, and fuel to operate at these speeds, but 12 to 15 knots fuel use is quite low, but it is still a lot of horsepower being used. Here in New Zealand we have quite a few small power catamarans in operation which operate very efficiently at up to 15 knots. But they all have higher horsepower twin outboards, typically 40hp or more per side.
?
A the best with planning for your new project.
|
Hi, ? I’m the builder of the ECO 85 powercat, which is still under construction. I’m building my own electric outboards which are 3 Kw 48 Vdc each. Battery will be a 48 Vdc Lithium 300 Ah. There are 6 solar panels on a water cooled roof which will give a max power of about 2200 watt peak. ? If you have more questions, please ask. ? Regards, ? Jack ?
toggle quoted message
Show quoted text
Van: [email protected] <[email protected]> Namens matushonko111 via groups.io
Verzonden: Sunday, March 30, 2025 3:55 PM
Aan: [email protected]
Onderwerp: [K-Designs-Multihull-Sailboats] A newcomer's questions: More motoring-optimised liveaboard cruiser?; Assembly by water?? we are a young couple considering building a boat as our home after we finish our studies. We have found that Bernd's designs, particularly the KD860, seem to tick many of our boxes in terms of comfort, layout and cost.? There are two questions that arose, which we did not find answered on this forum yet: A) although we are likely to stick to the cheapest propulsion option (assumed diesel outboard) at first, the long-term ideal (we assume) would be a solar-electric drive, using better bulk energy storage than batteries (hydrogen, formic acid, methanol fuel cells... we are chemists, and so open to experimentation here). ? ? ? The question then is: since based on the 'Hull speed / motoring kd 860' thread that boat doesnt do well under power, how hard of a tweak would it be to make the KD860 a better medium-speed (<15kn) motor boat? Or are there any other designs with comparable accomodations, sea worthiness and cost that would be better suited to this role? (I have found the Eco85 powercat threads, no expected specs/material costs/layouts though, and we like the compartmentalisation/layout of the KD860). B) we unfortunately live in the smack middle of Europe- even a trip to the Danube (our only navigable river) is 100+km. It was mentioned in the thread 'weight of hull KD860 - moving' that transporting the hulls and center separately is possible, though not ideal- 100h asssembly, 250h finishing. ? ? ? What is meant by 'finishing' please? Is the boat liveable by that point? How much complication is added by such an approach, and what are the requirements on the place of final assembly in terms of space, equipment etc? (Ps. I know the default answer is that companies exist that can transport finished cats, but we are on a tight budget, and live in eastern europe where a French business may ask premium. Apart from that, we would like to have a fallback plan.)
|
Hello David
?
Thank you for falling in.
The hull shapes I draw are semi-displacement, with a high slenderness and good flat exit angles for low parasitic resistance. As you mentioned, it is a question of horsepower.?
?But how far will you go?
Electric propulsion is still too expensive in my view. Besides that, it is more complicated than prone to failure. An outboard engine, you mount and are ready to go. ?
To get a reasonable range, the batteries need to be very big. If somebody makes the argument that they want to do something for the environment, forget it. General pleasure boats are used to less as to have any positive effect on the environment when electric drive systems are used. I do not talk about the cost difference. Using solar panels plus a small wind generator for the other application on board is, of course, a good solution.?
?
You are content with your new boat.
?
Regards? Bernd
|
Hi
?
The hulls are semi-displacement hulls, which are, by design, fast. The KD 860 is very fast for its size. ?But when you can reach the speed under sail, you can reach this speed under engine. I understand that you do not have a lot of experience sailing a fast multihull. Here is a small example. Our Pelican was very fast, but when we were preparing meals, we reduced the speed to around 11 knots for an easier (safer) ?movement of the boat. For a life on board, lengthen the hulls by 8 %. Scandlings will stay the same. The boat would then be 9,18 m long. Gives a bit more space for living on board. There were builders who had the same problem. ?To build the hulls, mast, beam, and aftbeam. Transported the parts near the water and assembled them. Good, you can close the boat then in about 250 hours. But the boat will not be finished. All the time-consuming interior work has to be done. Toilet and shower room, seat bench, kitchen units, etc. There are a lot of pictures, just from building the KD 860. Look them over to get ideas. For a diesel engine, look at the Icarus built in Tasmania. He placed the engine just after the entrance bulkhead to have less weight at the transom for a good boat trim. ?
David answered some of your questions, too.?
?
Cheers
?
Bernd
|
Greetings,
We want to thank all of you for replying to our questions. We are still a bit lost in the 'what do we want and how do we want it' phase, and greatly appreciate any and all information.?
?
As for the (currently strictly hypothetical) solar electric part, yes batteries have many, many problems- I personally remain deeply critical of our civilisation's claimed goal of being powered by lithium ion. We did not intend to use those: they are too expensive, short-lived, dangerous and a few zeroes off in terms of energy density.?
However, there are 5+ alternative ways to store power in a 'rechargeable' way, all better in most ways vs the conventional battery tech, in various stages of 'work in progress'. Organic fuel cells, metal air batteries, different ways to store hydrogen... For instance, methanol (fuel with half the energy density of gasoline) can be made with electricity, air and water- with current research working out how to make the electrodes durable enough for common use. When they succeed, a 'solar electric' would just be a power boat able to slowly make its own fuel.
?
? ? ? ?I apologise for the text wall, just little frustrated none of this is part of the public debate (or funding) with batteries being the only, and worst, option. It could make for an interesting separate thread perhaps. Considering the above, we wanted to make the boat in such a way that it could be a test bed for some of those emerging technologies when it comes to it, therefore the powerboat question.
?
It is great to know road transport of the semi-finished thing is possible. How much construction time/complexity would the extra 8% add? Also, I haven't been able to find the materials list for the KD860. Is it available on the website please, or part of the study plans?
?
Thank you,?
With regards, Matus Honko
|
Matus,
?
Phil Boyer has many videos on YouTube about electrifying boats
?
?
Maybe help
?
Best regards, Eduardo.
?
?
De: [email protected] <[email protected]>
Em nome de matushonko111 via groups.io
Enviada em: segunda-feira, 31 de mar?o de 2025 09:59
Para: [email protected]
Assunto: Re: [K-Designs-Multihull-Sailboats] A newcomer's questions: More motoring-optimised liveaboard cruiser?; Assembly by water?
?
We want to thank all of you for replying to our questions. We are still a bit lost in the 'what do we want and how do we want it' phase, and greatly appreciate any and all information.?
As for the (currently strictly hypothetical) solar electric part, yes batteries have many, many problems- I personally remain deeply critical of our civilisation's claimed goal of being powered by lithium ion. We did not intend to use those:
they are too expensive, short-lived, dangerous and a few zeroes off in terms of energy density.?
However, there are 5+ alternative ways to store power in a 'rechargeable' way, all better in most ways vs the conventional battery tech, in various stages of 'work in progress'. Organic fuel cells, metal air batteries, different ways to
store hydrogen... For instance, methanol (fuel with half the energy density of gasoline) can be made with electricity, air and water- with current research working out how to make the electrodes durable enough for common use. When they succeed, a 'solar electric'
would just be a power boat able to slowly make its own fuel.
? ? ? ?I apologise for the text wall, just little frustrated none of this is part of the public debate (or funding) with batteries being the only, and worst, option. It could make for an
interesting separate thread perhaps. Considering the above, we wanted to make the boat in such a way that it could be a test bed for some of those emerging technologies when it comes to it, therefore the powerboat question.
It is great to know road transport of the semi-finished thing is possible. How much construction time/complexity would the extra 8% add? Also, I haven't been able to find the materials list for the KD860. Is it available on the website
please, or part of the study plans?
With regards, Matus Honko
|
Hi Matus
?
I do not reflect on the electric drive issue. You see for yourself how uncertain the future of the e-drive is.?
When the hulls are 8% longer without increasing the beam, about 100 hours will be needed.
Because of the bigger inside room, it is up to you how much more work you will invest because of the gained space.?
?
Cheers
?
Bernd
?
|
Hi to all,
I also have not posted in a while. I have started my hull extension on my Eco5.5 to go from 18' to 20'.
This was a bit controversial, but I decided to go ahead with it anyway. I have the extensions independently built over the winter. The next step is to sand the existing hull down to add them. The attachment point will start 6' back from the stern. I have also
modified the bow to go back to a curved bow so that weeds in the canal do not accumulate around it.
As for batteries, I bought qty 16 of 202 Ahr LifePo4 batteries in the Spring of 2020 and paid a total of $3200 CDN. They are still good but are now at about 90%. It is not the cycle life you need to consider but the age degradation of Lifepo4, but even with
age they still work.?
I just received a few weeks ago new 302 Ahr batteries and paid a total of $2100 CDN. So, 1/3 more power for a 1/3 less cost as batteries are getting cheaper all the time. There are more electric motors available in 2025 but are still double the cost?of a gas
motor. This will change in the future with mass production.
I am documenting the modifications on my YouTube channel as I get ready for a new season. This year I will be touring the 1000 Islands and the Rideau canal for two weeks using only solar electric power.
Regards
Phil Boyer
|
Hi Phil,?
Nice hearing from you.?
Thanks for chipping in. You have a lot of experience with electric solar-powered boats.
I see you are busy lengthening the boat.
?
Here is a link to his YouTube channel, or in the middle of a journey. https://www.youtube.com/watch?v=1eyJUnSCYms
?
Success with your new plan for this year.
?
Cheers
?
Bernd
?
|
Here is a link to my You Tube channel where I have documented all my trips using solar electric power.
|
|
Share your videos with friends, family, and the world
www.youtube.com
|
Phil
|
Nightline
Bernd Kohler