Crowther design 226A (42 foot cruising cat)

[Corley]

Now thats funny.

So you are still buying core and epoxy and sheathing the ply in glass and fairing it then painting it.

(have checked out the price and properties of the latest generation poly and vinylester resins)

Out of interest do you know what type of glue has been used in your cheap plywood?

So remind me again where the significant saving is.

I've had the ply tested it meets the psi requirements and it passes boil test, I don't grab any old sheet but sort through the piles carefully and pick the best. I've made some test panels with the material and it's satisfactory and fits within the material properties required. Foam core is also very expensive if you want to buy the good stuff. Yes, you still need to sheath, fair and paint plywood but you have to glass foam or balsa core as well as fair and paint so you don't get a free pass from any method. With Kurt's designs you don't have to use core it's optional you can use stringers as a substitute. If you scrounge well enough you can even get decent used materials to use for that and machine to the correct sizes with your own woodworking tools if you have them. Since your apparently flush with cash you clearly don't have to think about that.

If you read my previous replies I was suggesting that he look on the secondhand market rather than build because there are well built boats that need repair and are worth the time and effort if reviewed carefully. He also notes that he is struggling with the cost of plans. That's not encouraging as far as the cost of building a boat and buying the materials required either.

 

[CloudDiver]

Ummmm..... so I'm not going to get involved in the above posted.... er.... discussion; but I do want to clarify a few things.

First off, I was a little confused. The Spindrift 37, Spindrift 40 (also called the Crowther 40), and Design 226A which is 42 ft, are three different designs. I was under the impression that the Crowther 40 was just a stretched version of the Spindrift 37 and perhaps I am right about that, but in any case I have found separate drawing (not plans) for each. And then the Design 226A is 42 ft and quite a bit of an advancement in overall design aspects from the Spindrift, although easily recognizable Crowther lines.

That said... I won't be building in wood. I've built many small craft in wood and although I love it as a classic, strong, and beautiful material I won't do it in a performance Cat. In the US, certified ply for boat building is in most cases equally as expensive as sheets of PVC80 foam core. I have actually sourced Airex C70 and a PVC60 at a lower price than BS 1088. There are some serious import costs on wood to the US right now and I'm afraid it will only get worse. The PVC60 I have found is from a US manufacturer, and while it has lower compressive modulus than PVC 80 I am only exploring the possibility of using a thicker core (19mm vs 16mm) to make up the difference and have a stiffer structure via the thicker foam core.

I do greatly appreciate the compressive and sheer strength of end grain balsa, and I have sourced 4 x 8 sheets of it for about 20 to 25% less than other name-brand core foams. My problem with blasa is that it still yields a heavier core structure if you are not meticulous in your lay-up schedule, but primarily there is a negative stigma in the US to anything 'wood' in core materials. I know this is very unfair since it is not the result of the material properties but rather shoddy workmanship, but the average uneducated boat buyer in the US will run away from a balsa core Cat like it had the plague even if it was built by the same guys who construct America's Cup boats, LOL. I will building this Cat for myself for the long term, but I'd be stupid to not consider future re-sale value... and just like my former collection of motorcycles, you can never have just one!

So right now I am fiddling with a 4 x 8 CNC panel router. I have roughed out plans for a machine that will have a roughly 20 ft X axis and an 8 foot Y axis, only 4 to 6 inches is required on the Z but I'll probably get 12 to 14 on the Z to shape foam blanks. Anyway, that is why I am attracted to the Schionning Arrow Cats, the flat-panel construction method. I'm awaiting continued updates to Tony Grainger's new Raku Cats as well. The seem to be flat panel above the water-line but have rounded bilges. Whatever I decide to do, I will likely utilize my plans for a large flat panel CNC router. Luckily I have enough room in my home shop for this machine so I can manufacture and store my own 'kit'. When I get on to building I will be selling my home and moving out the country will land is a bit cheaper, LOL!

The Crowther designs intrigue me and I just thought it'd be worth looking into. I might build a 25 ft sport Cat just for shits and giggles but also to get my processes refined before I dive into the big Cat. I'm not really balking at the $10K cost for Schionning's plans, but realistically I think I could buy all the materials (epoxy, S Glass, and core foam) to do the 25ft sport cat before I invest in the larger plans. In the long run, I think I could build a Crowther design with an alloy rig for much less than I could build an Arrow or a Raku, but still be very happy with its sailing ability. Seriously guys, I like the idea of high performance but my goal is efficient passage-making and storm avoidance, not winning races (but that would be fun!). i.e. I don't yet have the skill of a seasoned multi-hull racer, the only multi-hull I've sailed is a Hobi-Cat.

 

[Corley]

The Arrow and Raku designs could be a good choice, you would have to look carefully into the cost of making or cutting your own panels versus the precut kit sometimes the cost gap isn't what you would think on initial appraisal particularly if glass reinforcements and consumables like epoxy and fillers are included in the deal. I made some enquiries on a kit for a Spirited 380 race catamaran and the kit was around the 30k AUD mark for balsa cored duflex and included full plans, glass tapes, bulk west resin and fillers. True it's a simple boat with no bridgedeck so less surface area but still not too bad I thought.

 

[CloudDiver]

The Arrow and Raku designs could be a good choice, you would have to look carefully into the cost of making or cutting your own panels versus the precut kit sometimes the cost gap isn't what you would think on initial appraisal particularly if glass reinforcements and consumables like epoxy and fillers are included in the deal. I made some enquiries on a kit for a Spirited 380 race catamaran and the kit was around the 30k AUD mark for balsa cored duflex and included full plans, glass tapes, bulk west resin and fillers. True it's a simple boat with no bridgedeck so less surface area but still not too bad I thought.

The Arrow 1280S kit price is 90K USD with container shipping from South Africa. I have a quote from my Schionning for this but I also have a friend who has already purchased and begun construction of his kit on the east coast. I have broken down the contents of the kit in terms of total kilos of glass fabric, core foam sheets, epoxy by the drum etc... $90K isn't too bad if you consider the CNC cutting and the time savings, when you get a kit you will have a nearly complete structure in very short order compared to traditional building methods. To be fair, a pretty big part of the cost is labor and CNC time for the kit. Container shipping plus on site delivery worked out to about $7500 from S.A. to Port of Baltimore and then a hired roll-back truck for delivery. The container itself was purchased so that it did not have to be returned and used as an on-site storage locker.
There is huge potential saving in buying the kit for certain types of builders, but not for me. I am a bulk buyer so I will be getting the same or better prices for epoxy, core foam, and roll quantity glass fabrics than any other builder would get. I also have my own organic CNC capability. My biggest reason for wanting to manufacture my own kit is to address what is, IMO, the biggest flaw in this construction method. In the Schionning kits that are made by ATL composites or other sub-contractors; the full lay-up schedule is vac infused to both sides of the core-foam in 12.5 meter sheets then loaded into the 12.5 m X axis CNC panel router for cutting. Everything sounds all good up until this point. The panels are cut... the UD fibers are cut... cut! So you then assemble the kit panels and yes the method is rather rapid which I do appreciate. The problem is all of those seams. Yes, they are taped and other reinforcements are added, but for the most part the full lay-up is pre applied to each panel and cut. Unless I am missing something, (because I haven't built this kit), there is a lack of uninterrupted UD fibers. My concept would be to infuse the minimum amount of laminates on either side of the raw core sheets, just one layer 0f 1708 bi-ax if possible. The purpose of this is to make the sheets the minimum stiffness and toughness to be handled and loaded onto the CNC bed for cutting and later assembly without damage. The ultimate full strength of laminate would be achieved with serial infusion of the longest clear spans of uninterrupted fibers as possible in bi-ax, tri-ax, and UD cloths. I can modify my CNC router with a drag knife to cut patterns in dry cloth... not sure how that will work since I have never attempted this but as a back up I can modify the CNC into a plotter and just mark the fabric for manual cutting. Point is, I want clear spans of uninterrupted fibers for the full length of the intended target surface and over all seams, not a frankenstein of panels and tapes.
I realize that my intentions for the lay-up will actually add hundreds if not thousands of potential labor hours... but my personal time comes at no cost in pursuit of the strongest & stiffest structure possible. I will have to pay the cost for additional labor but I believe it is worth it for a better hull and I will likely save time in fairing all those seams!

 

[Corley]

You might find some useful information in gropers 10m efficient Powercat build thread. He infused his panels on a table and there was some labor savings in the process. efficient 10m displacement powercat (build thread) https://www.boatdesign.net/threads/efficient-10m-displacement-powercat-build-thread.38588/

 

[CloudDiver]

You might find some useful information in gropers 10m efficient Powercat build thread. He infused his panels on a table and there was some labor savings in the process. efficient 10m displacement powercat (build thread) https://www.boatdesign.net/threads/efficient-10m-displacement-powercat-build-thread.38588/

Thanks, this a great resource...

 

[xrudi]

I have a Crowther 226 and would like sell it.

 

[xrudi]

This boat was working as a charter boat in Malaysia and Thailand. Here the brochure and specification.

 

[xrudi]

Here is my Crowther 226 build to GL standard. It is an excellent

boat. Build in a female mold.