Coastal Cruiser

Well done Rick. A most interesting project. I hope you get all the sponsorship you could use.

 

Market share

In general people like a more open cabin design.

Perhaps you could move one of the solar panels to the aft deck, remove some of the side windows. Create an open cockpit more to the center of the boat, this would also help the weight distribution considering that crew mass will be a major factor in the equation.

 

SeaSpark
I appreciate the input.

The boat has been undergoing development since these posts. It is now 12m long; central hull 6m and ends each 3m. The beam has increased to 1.8m overall and displacement now at 1100kg. There are six solar panels mounted 3 long and 2 wide. The windscreen is now close to vertical.

The cabin will have two bulkheads that partially divide it into 3 sections. When I get around to it I will post an up to date view.

The other big change is to use a long shallow keel to carry the batteries. This, combined with a bit more beam increases the stability markedly.

It is shaping up to be a practical concept for composite construction. Just have to get into structural design now for the connection points.

Rick W.

 

Interesting. Does this possibly mean the 'box keel' mentioned in the 'propulsion-hybrid' thread may have some value for other designs? Or am I just not understanding you?

 

Harry
It is simply a long keel to get the batteries as low as possible, shaped to have good structural strength. It does not have much volume and adds to the drag but is a compromise to improve stability.

It is not in any sense like a box keel. Overall the boat hull is very much like a canoe so is a low drag hull.

I will post an image when I have done more work on the changes.

Rick W.

 

AS an enthusiast of long slender hulls , the question of stability at anchor has come up.

The solution we seem to be gravitating towards is to use a pole as outrigger and simply use the dink to stiffen the boats roll when aboard at anchor.

FF

 

I too am an enthusiast of slender hulls and wave-piercing bows. However, why do you feel that a piercing-type bow is necessary for a boat with a top speed of only 12 kts? I assume that the 12 kts top speed you predict is only expected in fairly good conditions. In that case, I imagine you'll be doing something closer to 8 kts in the kinds of conditions that would call for a bow of that type in high-speed applications. Why not use a traditional bow? You could increase interior volume while also increasing stability (from more beam running farther forward) and therefore obviate the need for added overall beam.

Have you given any thought to the (heavy) reinforcement required for the cabin front and windows? I'd guess those windows could see in excess of 30 psi from breaking waves, though probably less with the forward slope.

Just some thoughts.


~ ALowell

 

The underwater hull is the product of Godzilla optimised for 10kts and displacement of 1100kg with KMT 0f 1.3m. That is simply the most efficient shape for calm conditions given these basic constraints.

It should end up more stable than FFs Atkins hull given how I can place the batteries and the cross-sectional shape.

Rick W.

 

Looks nice Rick, it should work too. Just one think I don't like about the idea is that is is going to roll about being a mono hull. Personally I would strongly consider adding sub hulls, the loss in speed due to extra drag may well be worth the stability. 48V should be more efficient than 24V, for one half the voltage drop (and heat losses) over the wiring used..

 

Fred
The motion of a boat does not bother me much for sleeping.

My worst night at anchor was when mored in a tidal passage and the wind came up and blew straight up the passage against the current. Deep keel yacht held stern to the wind and small dinghy kept surfing into the stern of the hull. It made great thumping sound every time it did this. Don't think I actually slept the whole night.

My most common problem sleeping at anchor was the damn clanging of halyards around masts. One reason never to have internal halyards. I guess it is not as bad with a CF mast.

Rick W.

 

Come on Ricky!!! Won't you please go up to a waterline Beam of 2m?? Come on man, do it for ol' Jerry, eh?

 

Sorry Rick, Seems madness has set in so Mad Masa can enter???

With an loa of 12m & beam of 1.8m, would not a more stable platform of cat with 200mm beam on each be all that is needed to carry 1100kg?

Also will allow location of screw & shaft to be midships & raised free of the water with a 2 bladed prop..... crunch the numbers with mitchelet/godzilla...

 

Brian
I rate self-righting very high for small ocean boats.

I like the idea of a boat that bobs up and down rather than rolling about to follow the surface of the water. You have to go really big to span a lot of water or use ballast in a narrow hull. I have chosen the latter because it gives the added benefit that it will eventually come up the right way.

The ballast also serves two purposes. It doubles as my energy storage system.

Rick W.

 

Along with your superior knowledge relating to screws/propellers, power demands, design-development of an efficient hull (with gentle support of Michelet et al) and solid analysis of your needs and design criteria I bow to your wisdom with grace and humble reverence...

Does not that sound like I would appreciate another favour? The probability is that I will, but you definitely deserve all praise received. Let me try again first, I fear "wine" is not co-operating in some aspects of communicating with Linux for some commands in interpreting Freeship and Delftship......

I will PM you later.... Thanks, masalai

 

I understand the underwater shape is governed by the efficiencies you want, but what about the above-water shape? Aside from some added weight, how would a traditional (albeit low buoyancy) bow affect the overall idea?

What's going to happen when this boat punches its bow into a wave and you have 2 feet of water over the front windows? That's a lot of pressure over a large area. It would only take a very minor change to the bow to significantly reduce the likelihood of this happening.

~ ALowell