I'd like to express my sincere gratitude to Bernd, the masterful designer and moderator of this forum, for letting me bring in some unorthodox thinking, despite the obvious sliding off topic.
|
Ah, something to add to a high speed watercraft ramblings (well, sorry, seems so offtopic).
There is an excellent Turbowing concept tested and proven by late John Malvestuto.?
Ingeniously effective at the expense of more noise from overhead propeller.?
|
I tend to agree: it is a state of mind willing to optimize any design to suit personal requirements.
Myself thinking about merging nice accomodations plan of Bernd's excellent Eco6 and 6.5 powercats with marvellously seaworthy and proven MIG-welded aluminum planing hulls of StormCat 21 design.
( Can be found here:
This quest is driven by prevailing local oceanside conditions: +4 degrees Celsius summer water temps, mostly rough coastal conditions- Bf force 3-4 commonly and running off the gales is always a good idea.
MIG welding waterjet cut aluminum plates is a real fast build compared to gluing/fiberglassing/fairing/painting and makes for a stronger and longer lasting result.
By the way, it is not overly expensive to hire alu welding professionals.
Some nice introduction info on the technique can be found in Downloads section of this website:
https://www.platealloy.com/downloads.htm
I really praise those downunder folks pro skills and helpfulness))
And there is, as I see it, some way to optimize and further increase seagoing and practical qualities of StormCat concept.
I think adding hovercraft air cushion bag skirt, like on Sevtec Explorer/Mariner designs, can help achieve some nice things like:
1) more speed;
2) less outboard rpm when riding on cushion, e.g. less fuel to burn;
3) plush ride in rough seas with more speed (based on Sevtec owner reports);
4) ability to ride up and down the beach;
5) more load carrying with less power (Sevtec drag polars do confirm this guess);
6) possibility to lighten the structure and save on welded hulls weights thus balancing the Eco-type accomodations structural weight.
The yet unknown part of this concept is a design of remotely lowering outboard supports at transoms, since the air cushion lifts the hull bottoms some 30 to 40 cm above water plane. Some hydraulic system may need to be involved in that.
Also, some remotely lowering centerboard seems necessary for directional stability on the course and better turning habits.
|
Hi Bernd and Brian
Thanks for the direct reply from both of you. I liked the Kd105 From the first time i saw it. the design has that simple but apocalyptic and fast look.
Longer time ago i was looking at Wharrams Classic designs, and to be honest, i like the style and mostly huge (open)deckspace. But not their sail performance.?
Also i looked at other designers but all you can find in around 40 foot, are bridge deck cats with lots of inside rooms and corners etc.
The living space in the hulls is not so important for me. here in the tropics you wont live in there anyway. The hulls would be more for a guest and storage of clothes etc.
The quite big nacelle of the kd105 would be for sleeping relaxing and cooking.
That`s why i asked if the design could be stretched so i could gain more open deck space fore and aft the nacelle. That would be our living space when not navigating and covered by a tarp or tent ideal for the sun and rain protection. And i guess i will gain some more loading capacity by stretching the hulls. Another welcome fact.
Another part that attracts me to the design is the shallow draft. I don`t want to use dagger boards, sailing here between islands and coral riffs most of the time. That`s why i like the asymmetrical hull shape you use on some of your designs. I don`t know much about trapezoidal hulls tho.
The Duo 1000 i don`t like so much although it has everything you would need, but in my opinion that is exactly what i don`t like, too much squeezed in a 10mtr cat.
As you all know it is not an easy decision to make, trying to find the best design to suite your needs and what you capable to build and afford.
|
Thanks Bryan,
I am still coming to grips with how this messaging system works. I don¡¯t understand it yet. I will try as you suggest
Cheers
Keith
?
toggle quoted message
Show quoted text
From: [email protected] < [email protected]>
On Behalf Of bryanandmarycox via groups.io
Sent: 12 June, 2022 7:59 AM
To: [email protected]
Subject: Re: [K-Designs-Multihull-Sailboats] KD105 extra info pls.
?
Keith
I dont want to sabotage this topic on the KD105. Why dont you briefly describe your circumstances in a new threat with a topic like " most suitable smaller design to suit my situation" or similar. Quite a few of Bernds smaller cats have been built.
cheers,? Bryan
|
Keith
I dont want to sabotage this topic on the KD105. Why dont you briefly describe your circumstances in a new threat with a topic like " most suitable smaller design to suit my situation" or similar. Quite a few of Bernds smaller cats have been built.
cheers,? Bryan
|
Hi Jan
?
I know, there are not many photos from a KD 105. K-designs is a one men's operation, from the toilet cleaner, the designer, to the general director. So I can and have not built all my designs. I depend on photos or videos of the clients. I have only to a small part of my client's contact. It is also impossible. For instance from the SC 435 more than 1000 plans are sold, spread over the world. Or for instance, I get from the KD 860, sometimes photos or videos clip from persons I have no idea.
The KD 105 is not different. So there is simply no more photo material.
To your questions. The KD 105 has symmetrical hulls, like for instance the KD 860.?
Anyway, when demontability is not necessary, and regarding, how you would like to use the boat, the DUO 1000 would be a more logical choice. See https://ikarus342000.com/DUO1000Spage.html for the first information.?
By the way. Slats on deck are not the best solution. My friend Henk de Velde was sailing around the world in an ORO from James Wharram. In his book ¡°Gamzen trekken in troepen¡± he described how he and his wife were trying to refasten the deck slats in a storm, so as not to get washed away through the arisen openings.
?
Cheers
?
Bernd 
|
Moderated
Re: Thinking about building a Manta
Hi
?
Short, you are right, the CWL shows the loaded weight. So you have a load capacity of 2400 kg. (2,4 tons)
I am wondering about the weight of your equipment for diving. Ours was around 150 kg.
We are all the same. Putting things in the boat and never taking them out. On his nonstop attempts to sail solo around the world, Henk, the owner sailor of the Zeeman, was throwing out the pages he had read in a book.
A bit overdoing, but a good reminder.??
Cheers
Bernd
|
Moderated
Re: Thinking about building a Manta
Hi Bernd, and all. Thanks for the valuable info!
Overloading here means exceeding the c.w.l weight, correct?
Nice weekend to all of you.
|
Moderated
Re: Thinking about building a Manta
Hi All.
Thanks for the input so far.
I do understand now that I need to keep a big eye on weight. Event more I thought before.
Well, the bronze portlights are more mentioned as a general inventory here then. :-)
Ok, the point is: I see the 'weight empty' at Bernd`s webpage. And the weight c.w.l., which I should not exceed, correct?
Build as light as possible, but it would be ok to reach c.w.l.?
I now how quick weight adds but now I'm not sure about how realistic my approach for the Manta is.
Main points of weight here, in my plan, for me:
- I plan to go for (diesel) electric propulsion as I do have two LiFePo4 batteries of my house. Each with ~15kwh capacity. The genset has about ~200kg all in all. Batteries, I will check when I get back home.
- Two electric engines (which are not too heavy)
- Some diesel. I assume the diesel electric version not to be heavier than two diesel engines.
- 250 l of water + water maker
- Diving compressor and equipment -> around 450kg-500kg
- Up to 5 persons
- Some tools
+ All the bits and pieces
|
Hi Brian,
I have just purchased the drawings for a 520 Duo. I live in Rotorua and my closest harbour is Tauranga. I think you sail on Tauranga and I liked your 480c. I have a mooring in Pilot Bay currently leased out. I bought
it years ago with the intent of one day being in possession of the time or money to put a catamaran on it. I am nearly as old as Bernd (79 this year ) and think I may be running out of time. The 520 is not very spacious and though I am confident that I could
build it I have been looking at the 750 which is bigger but not impossible. My partner and I have previously owned first a Raven 26 then a Young 88, we both enjoy sailing.
Any advice?
?
Regards
Keith
?
toggle quoted message
Show quoted text
From: [email protected] < [email protected]>
On Behalf Of bryanandmarycox via groups.io
Sent: 11 June, 2022 8:45 AM
To: [email protected]
Subject: Re: [K-Designs-Multihull-Sailboats] KD105 extra info pls.
?
Hi Jan
I wouldnt have thought this design would be the best choice for a live aboard, even stretched. Theres only the nacelle for any real living area. Bernd will reply better than me but I recall looking at the drawings when Bernd first came out with this one as
I do with all his new boats. Other small parts of your questions: the boat is trapezoidal so it is not asymmetrical hulled. It certainly is an interesting boat. Good luck
|
Hi Jan
I wouldnt have thought this design would be the best choice for a live aboard, even stretched. Theres only the nacelle for any real living area. Bernd will reply better than me but I recall looking at the drawings when Bernd first came out with this one as I do with all his new boats. Other small parts of your questions: the boat is trapezoidal so it is not asymmetrical hulled. It certainly is an interesting boat. Good luck
|
Hi to all.
Love the KD105 design. Only a shame there are no pics or info of any build-and-finished ones around. On the 3D screenshots its hard to see and imagine how it`ll look and sail. For instance most screenshots don¡¯t show
if the hulls are a-symmetrical. Only one shows it slightly. Are the hulls less a-symmetrical as for instance the kd860 or kd122 ? The (open) space between hull and cockpit on each side is supposed to be (closed) with netting material as well as the trampoline
in front of the nacelle ? So if you have go to the mast you have to walk over and stand on the net (trampoline) whilst hoisting your sails ?
On the study plans I bought some time ago, I get some specification as to the alu. beams but not for the mast and rigging.
I live in the Seychelles (small island group indian-ocean) Often it is hard to get good second hand material/equipment when it comes to specific specifications. And importing, let`s say a complete 13mtr mast with shipment and import duty
+ Vat also over the shipping costs, it will be too much I think.
If I could get more specifications about what I need for the compete rigging I could try to go around to see what is available at the moment. This would be for me crucial to make a final decision of going for this design.
Coming to my final question, I should explain first a bit about me.
Going to start next year building a cat for my wife and me to live on. We don¡¯t need much luxury and bulky space but we need useable space outside here in the tropics.
We are not planning to make huge crossings or even leaving Seychelles territory. Most inner islands here are between 20 to 80 nm. And maybe with the proper season and weather we`ll sail to the outer island about 300 to 600 nm from the main
island.
I was looking before at Wharrams Tehini and love the huge deck-space it has. And that is why I wonder if it would be possible to stretch the KD105 to about 40+ foot and gain more deck-space in front the nacelle between nacelle and trampoline
for wooden slatted floor as well as some longer cockpit area. As well as some space in the hulls and maybe even gaining some loading weight? ?Without changing performance and safety aspects.
For a designer like Bernd it should not be impossible to draw something like this up, but I have no idea how much work for him it would implicate thus how much it would add money wise to the project.
The extra work and material costs for building a larger version, would not be so much and it`ll be the perfect boat for us to live-on.
Any thought or info would be much appreciated, thanks, Jan Hugelmann.
Sent from for Windows
?
|
Moderated
Re: Thinking about building a Manta
Hi Pepijn
Thank you for reminding me that there is a video sale that shows the Manta very well.
I agree with your remarks. The mast support is changed in the plans after your advice. And yes, whichever catamaran you are building, building as light as possible is very important. Not overloading the boat the also. Speed of the boat, respectively, to accelerate very quickly is a safety factor for multihulls.
?
Cheers
?
Bernd
link to video Thank Pepijn?
for reminding me that there is a video sale both which shows the Manta very well.
I agree with your remarks. The mast support is changed in the plans after your advice. And yes, whichever catamaran you are building, building as light as possible is very important. Not overloading the boat the also. Speed of the boat, respectively, to accelerate very quickly is a safety factor for multihulls.? Link to the video https://www.youtube.com/watch?v=nHs2CNrIJ28&t=14s
?
Cheers
?
Bernd
|
Bernd Kohler <ikarus342000@...> added folder /MANTA video
|
Moderated
Re: Thinking about building a Manta
?
On 06/07/2022 5:25 PM domenicodispaldro@... <domenicodispaldro@...> wrote:
?
?
Welcome Marc
I am pleased to hear that a member of the forum will build the Manta.
I'm curious.
Hello
|
Moderated
Re: Thinking about building a Manta
Hi Marc, excellent choice! Superb safe and tough design. I lived a few years on the Manta Lucia (you probably still can find the advertorial movie on YouTube somewhere). But as you sum up your materials you plan to use I get worried. Please be aware to leave every possible kilo ashore. Build as light weight as possible. A heavy manta is a sitting duck. 50m of 10mm chain??? OMG!! No! Bronze port lights, nonono! Not kidding here.? The ventilation system Bernd put in the design is very smart and working great. Be sure to reinforce the mast support a bit more than by the original design. Make a cabinet under it to create a compression box or something like that. I wasted mine sailing in a gale once.? Looking forward to see your building progress on the forum!
toggle quoted message
Show quoted text
Op 9 jun. 2022 om 15:24 heeft domenicodispaldro@... het volgende geschreven:
? Welcome Marc
I am pleased to hear that a member of the forum will build the Manta.
I'm curious.
Hello
|
Moderated
Re: Thinking about building a Manta
Welcome Marc
I am pleased to hear that a member of the forum will build the Manta.
I'm curious.
Hello
|
Moderated
Re: Thinking about building a Manta
Hi Marc!
I am very excited for you and I wish you joy and resilience in the process. I look forward to seeing your pictures and maybe even videos.?
I will let the others who live closer to you answer your questions.
Cheers
Patrick
s/v build Dulce Refugio?
|
Good morning fellow people,
my name is Marc. We, my wife Lilli and I, are planning to build a catamaran. A Manta (or 'similar') would be lovely.
Yes, 3000+h is plenty, but we think we can make it with a 5th and 6th hand here and there in a year or so.
We would prefer the Manta or Cormorant over the KD122, because we plan to have some stuff on board and need 'carrying' abilities of the vessel and like the design. We plan to live and work aboard full time.
Until now, we repaired and refitted a steel boat (12m), repaired two other steel vessels in the canaries and built an aluminum and a ply dinghy. Basic woodwork skills and tools are available. Until now Lilli had the patience and I had the power for these builds.
From past projects and ideas we have plenty of parts for the boat -> 2 mast sections (148x220x3ish mm..could be sparcraft NG70...not sure) together 13.8meters (+ boom 3.9m + furler + traveler from a 16ton monohull from 1990. Could be a bit heavy, and until now I don't know the rig size, but might fit. Changing the mast fitting and building a 'tabernacle'/mast foot should be fine, as we are ok in welding Alu. Some new V4A screws and fittings and antiseize, some paint and it should be fine. Would have loved to build a junk rig, but we have the stuff, and so it is. For rigging in general we need some assistance.
Oven, electric + diesel Heater, solar panels, winches, steering wheel, 2 anchors + 50m of galvanised 10mm chain, daytank stainless, windgen, 1 dinghy, box full of bronze windows, plenty of aluminium and stainless stuff to build bow roller ect.
All of our stuff is in a 40ft container, which we may want to move to the building place.
Until now we have contact with Bernd and have bought the study plans.
Well, we are not particularly experienced in wood/ply-epoxy building. Beside the dinghy, which worked quite well and some youtube videos ;-)
So I have some questions to the community.
- Bernd recommends Okume plywood. Does it make sense to buy this with LLoyds/GL or BS certification? What would be a reasonable price at the moment in 'these times' for 9 and 12mm respectively?
- Do you have special Epoxy + Hardener + Glass recommendations?
??? - My current plans are to take as epoxy + hardener which is 'GL approved' but needs 'higher temperatures' to cure.
- I really don't want to vessel a boat which is later problematic to be 'certified' or 'accepted' also by insurance. Anything to consider here?
- From past projects we know: When the place and people are nice, building is much much more easy. So we are looking for a place to build.
Anyone here has recommendations for a suitable, nice, secure and not too expensive place near the water, preferably in Germany, Spain, Croatia, Greece? Arr, warmer Europe, near waters in general? ;-) Would be nice to have some boat builder/boatyard and 'help' not too far, just in case.
We are going to visit some places in the coming weeks but are thankful for whatever recommendation.
Any hint is highly appreciated. Thanks.
Cheers!
Marc & Lilli
|
bryanandmarycox
Bernd Kohler