Fast coastal cruising catamaran

In a Northern climate I wouldn't omit the cuddy. The Saturn cuddy is fairly small and could be handled by a few men. I was planning to build a demountable Gypsy with plans to launch and float the cuddy over to the hulls and winch it up into place.

The main problem in the US with using several mates to lend a hand is the liability you unwilling assume if someone gets hurt.

 

Are you for real ? you daren't get help because of legal action ? FFS !

"Only in America" as the saying goes !

I'm being gullible right ? It's a joke, must be a joke.

 

Thats why we sail to Canada and get our friends drunk for the big jobs. Then if anything goes wrong they are covered by National health care and we are already across the border. Of course in the NW it has been a lot of years since the Pig War so there isn't much likelihood of a international incident. Apparently we can take a case across the border at a time so plan ahead!

 

A better option for me would be to add easily removable tent like cuddy, something like you often see on open deck motorboats. Basically just enough to provide protection for helmsman from wind, rain and spray. If weather is good I dont fit it and have large open deck free from obstacles. If it starts raining or I have to push the boat hard to windward during high winds with spray flying everywhere I set cuddy up so helmsman have a nice dry place to sit.

 

I've lived in NZ which has a special accident program in addition to the national health plan. It's nice peace of mind if you get hurt, but seems to encourage all type of crazy behavior.

Back in the US I have a 10,000 USD excess on my health policy so try to stay safe. No idea what my friends have if anything. You'd really have to ask before you started work. some are teachers and state worked so they probably have low excess policies for a few more months anyway.

Jeff

 

I'm thinking the cuddy is needed for foul weather in port. If you get weathered in somewhere for multiple days, none of the boats you are considering have a decent saloon. Nice to be able to sit and ave a cup of coffeee and have a look around the anchorage, etc.

 

In case of bad weather at some anchorage I would set up a tent on a deck between the hulls. A large permanent saloon on a small 9 meter cat would be bad for upwind sailing performance. However a tent can be demounted when sailing leaving nothing to interfere with sailing performance.

 

The design I illustrated on the thread http://www.boatdesign.net/forums/multihulls/post-your-design-ideas-37103-8.html would seem to be quite a close match to your requirements, although at a nominal 10.0 m LOA it is a little bigger. Also, as drawn, there is a maximum of only 5 bunks, but one more could be squeezed in by making the seating in the port hull convertible into a double berth. Actually, I dont think provision for 6 persons to live on a 9 m boat can really be described as 'minimal accomodation'! My design does include most of the features you like - pivoting centreboards so you can run aground without too much damage - suitable for beaching and shallow water - demountable for occasional land transport - designed to be built in minimal building space.

I am spending the whole of the UK summer full time sailing so will not be doing anything more with this project until the winter months. If I do decide to go ahead and build this boat then it could be good to have another person(s) building to the same design - could discuss any problems (hopefully minor ones) and perhaps share ideas on sourcing materials and equipment. With that in mind I might consider sharing the plans with anyone who is genuinely interested, but havent really thought that far ahead at this stage.

 

Mulkari,

Are you familiar with the plans of Bernd Kohler?
Some of his designs seem to fit or come close to your demands.

http://www.ikarus342000.com/CATpage.htm

 

Could amplify more on how you will be mounting the beams securely between the 2 hulls? A 10m demountable cat is of great interest to me and a possible future build. I am currently sailing on a 7.5m version which is for me too small to have any real accomodation.

regards

guzi

 

I am away sailing so dont have my desk computer and CAD, hence will have to try to explain with words rather than pictures.

What I propose is as follows. The cross beams themselves are box girders with plywood sides that act as shear webs and wooden 'cap spars' at top and bottom. This is quite a simple and common way to make cross beams for a wood and epoxy catamaran. Each end of each of the two main cross beams slides into a recessed trunking in the hull structure. There are gaps between the tops of the cross beams and the tops of the trunkings, also between the bottoms of the cross beams and the bottoms of the trunkings. Pairs of wedges are located within these gaps. Each pair of wedges includes one wooden wedge screwed and epoxied permanently onto the top/bottom of the cross beam and one movable wedge which slides over the fixed wedge so as to jam against the trunking, vertically locking the cross beam at that point. The moveable wedges could be wood but I would rather make them from a plastic material such as Delrin. The moveable wedges are driven into place by tightening nuts on threaded rods. Although the compression loads on the wedges are a good many tonnes, the loads on the threaded parts are relatively small since the wedge angle is close to the self locking angle. M8 SS threaded rod should be sufficient and the nuts could be wingnuts tightened by hand, although I would include a nut locking arrangement for peace of mind. By individual adjustment of the wedges it is possible to adjust the relative orientation of the hulls in both horizontal and vertical planes, so as to compensate for building tolerances. One point to note is that there is a good and a slightly less good way to incline the contact surfaces between the wedges, one way gives lower contact forces than the other. This is a bit difficult to explain in words but anyone who has designed housings for taper roller bearings would know what I mean.

I am not claiming that there is anything all that wonderful about the above arrangement - much the same thing could be achieved by use of big bolts with adjustable shims to take up building tolerances. Indeed, I did first draw up a couple of alternative arrangements using bolts, but then decided that on the whole I preferred the wedges. When the structure of the craft is loaded under sailing forces at sea, the loads on the bolts would be such as to require careful consideration as to how these loads are to be transferred between the relatively small section steel parts and the much softer wooden structures. Certainly doable, but the wedge arrangement avoids the problem since the loads are passed all the way through relatively large cross sections of material, reducing stress concentrations and possible fatigue problems in metallic components.

 

It's a bit too big and I suspect empty weight will be much more than 1 ton requiring cargo truck for land transport costing a fortune if we decide to relocate the boat to some different sailing place in Europe. I want something that can be placed on a regular trailer and pulled by average sized SUV.
Ideal for my needs would be Stileto 30 http://www.stilettocatamarans.com/stiletto_30_catamaran_specifications.htm

Unfortunately it is only available as production boat with no plans being sold for home builders.

Looks interesting although I do wonder why he uses asymetric hull shape to reduce lateral drift instead of dagger/centerboards? If such arrangment is so effective then why other designers stick to conventionally shaped hulls and use boards?