45' solar catamaran

No, your connecting structure will sit lower and lower in the water and the waves will slap at it. There are a number of other negatives I could get at, but I don't see why you are usng a cat hull if you are not reaching for speeds above hull speeds.?

 

Space.
Space for a large solar array, space for big batteries.
To add, hulls efficiency, maneuverability, stability and other inherent advantage to Cat.

Thanks for your input. There is some great info.

 

The clear downside to the cat hulls for the project is the immersion issue.

If you sink her too low forward; you need to add bow extensions and if you sink her deep aft, sponsons, and if you sink her way deep, both.

The other downside and calculable risk is raising the vcg. This is very important because you also add windage and what you want to avoid it a boat vcg raising and then making it subject to windage. The couple in Nova Scotia who perished probably did this to their monohull sailboat conversion.

The thing about wind is when it gets under the panels; it can create lift and pick the boat up and if the vcg was already raised; the lift raises it more. Sometime captains or skippers think this is all managed by a wise helmsman, but it is not true. If you find yourself out in high winds; the boat needs to be evaluated for that limit and mitigation is in design, not during a high wind, high sea state. This means you know what happens under a beam sea say 2 meters and high winds, because you don’t want the wind under the panels to create sufficient force to put her over and there is some amount of wind that will…

 

All very true Fallguy

 

I noticed this at the beginning of your subject thread,...and I thought you might find interesting a couple of the major fabrications I chose for my little coastal trawler,..

Why Steel?

Why steel for the hull,...why not fiberglass like most other production boats these days? One of the key words here is 'production boat'. Sure making up the plugs, then the molds for a production run of boats makes sense. But what if you don't really know how many copies you may build,...what if its a limited run geared for a specific market?? Then you are trapped with an up-front, expensive bit of tooling that you can not amortize over a goodly number of vessels.

But if we still consider a fiberglass hull, we certainly know by now we don't really want, nor need, sandwich core construction in the hull structure below the water line,...for that matter we might well leave it out of the hull structure altogether. That leaves us with solid fiberglass construction utilizing some decent resins, some decent fiberglass, and some good gel coats. Great Harbor Trawlers brags that their hull bottoms are solidly built with “laminates of more than 1-inch thick”.

When I start thinking about the labor hours to lay-up the laminates of that thick solid glass bottom, and their cost of quality resins in today's new oil price market, I just have to come back to the reality that just as tough a hull can be fabricated from a single, much thinner thickness of sheet plate steel at a fraction of that cost. And the steel's ductility makes it all the more appealing.

Why steel? It's an inexpensive material, easily fabricated, and very durable. It's a material that inspires confidence in a boat's survivability from mishaps and collisions by both experienced boat owners and newly minted ones.


Can we build the steel hull shape we might want, and can we build it at a reasonable price? I certainly believe so. I believe we could build an almost identical hull to that existing one in steel. I also believe it could be made even easier by modifying the hull slightly to a single chine, or maybe even a double chine if so desired.

I would propose that this steel hull could be built in a 'frameless fashion'.
http://5psi.net/index.php?q=node/11
THE V/D STADT FRAMELESS CONSTRUCTION METHOD
This type of hull is built inside a frame rather than over frames. It is a very fast building method and I completed a 34ft hull & deck, completely welded and shot blasted and prime painted in 3 weeks flat






As noted the computer cut steel panels are welded-up together while supported by this external jig-frame. Then the internal framing members (stringers, frames, bulkheads) can be added as deemed necessary. I've attached another photo example of a bulkhead with stringers. I think the Pilgrim design could get along fine with 5 of these major bulkhead types tying the hull sides together, and supporting the thick sandwich-cored deck I wish to place on top of their upper edges.




Note that the welded-up hull, with the bulkheads all installed, could remain in the jig-frame fixture while the engine and other equips are being installed (no deck is installed yet). The deck piece, and then major cabin superstructure, could actually be assembled on another part of the shop floor and then brought over and placed onto the assembled hull.


There are several other advantages to this steel hull idea. You will note that I mention 'computer cut panels' of steel. This not only shortens the time of construction of the steel hull, it also makes it a potential kit-boat candidate.

It has yet another potential benefit. Unlike a fiberglass hull where I am married to a single bottom design, I can change this hull's bottom design readily if something new looks feasible.




***************************************************

Honeycomb Superstructure
Cabin Superstructure Construction

This is the plastic honeycomb material I want to utilize to build the superstructure(s), ie ….cabin sides and roofs




Plascore PDF
www.plascore.com/pdf/PP_Honeycomb.pdf

I'd like to use a relatively thick section of PP honeycomb (1 to 2 inches) to get a relatively stiff panel, with a minimum of layup of fiberglass skins on both inner and outer surfaces. The skins of this sandwich structure can be varied in their layup depending upon the required strengths needed for roof panels, cabin-side panels, etc. I don't foresee a need for big shear resistance in these panels that will be basically glued together to form the big 'box' structure of the main cabin and pilot station. Here are two illustration of that basic 'box' structure with bold lines to emphasis the structure.



Note also there is additional support for this 'big box cabin' via the vertical support tubes / columns that are anchored in the steel gunnels / bulwarks and then reach up to support the outer edges of the cabin roof. With these columns and the stiff panel walls there should be no other requirements for any internal framing inside the cabin box. Possibly there will be some additional corner braces added to the inside and outside of the 'cabin box', and these may appear as finishing-trim pieces.


This entire cabin box structure can be quickly assembled from pre-cut honeycomb sandwich panels off over in a corner of the shop, right on the shop floor, then lifted onto the deck of the vessel and glued or mechanically attached down. Built of primarily hollow honeycomb panels, this superstructure should be pretty light-weight.


There is no electrical wiring nor plumbing contained in the walls of this cabin-box. These services are all provided for by way of the floor of the cabin,....underside of the deck.


And speaking of the deck, I would wish to construct the main deck of this same Plascore honeycomb sandwich material. It would have a slight crown shape across the vessel, and will have sufficient glass layup on either skin to support big loads. It would also be molded by resin-injection to insure an excellent resin glass ratio, and a very thorough bonding between the skins and the core, thus preventing any water migration along the bondline.




For reference:.... previous postings on KSS construction of panels
post #109
post #110



Next,...finishing off these superstructure panels...

 

BTW, you might have a look thru a few of these discussions about 'silent chain drives'

Belt Drive https://www.boatdesign.net/threads/belt-drive.37290/page-3#post453137

 

Absolutely! If I had to build a complete boat right now, I admit that aluminum is tempting.

Sure it look like a good mechanical solution. But it's quite complex.
I'm really happy of my design who suppress any need of belt or chain ratio

 

I've start to cut windows frame in PVC foam with my little CNC.
Really happy of the result.

I will have to create thread in the PVC foam to fix the windows opening mechanism (blue circle).
I plan to add thickened epoxy to 4 oversize holes and create thread after.
Is there better filler than other to have strong thread?
I have cabosil and micro balloons in stock, but can find something else.

 

Aquaplas or coosa chunks also work and epoxy/cab them in place.

 

I'm not sure to understand.
My PVC foam is not that strong and Aquaplas or coosa don't seem strong either.

Sure your comment give me the idea to glue in place a stainless steel insert with 4 nuts, but it's a bit more complex than simply fill 4 holes with thickened epoxy after the fiberglass job.

 

I would avoid embedding stainless.

I have had good success drilling and tapping West 404, but for something like a large heavy hatch, I would epoxy in a chunk of G10 and drill and tap that instead.

 

That make sense. Thanks for your input.