CNC Plans not Included

yes Brian - the pacific 40 is the same as the solitary island catamaran, different in name only, sold by another company. Only 3 kits of the pacific island have been sold, the company that was selling these had bad timing in starting up just before the GFC. Only one has been completed that im aware of. My friends boat is now at high build primer stage. He doesnt have all that much left to go but yes its been a long slog - partly due to the difficulty in working with the polycore panels.

When i say "chines" i dont just mean underwater chines of a hull. I mean anywhere there is a change in plane between 2 panels. These exit everywhere - deck to cabin, hull to deck, chamfer panel to floor, a multitude of places throughout the interior and furniture, the list is endless... and everyone of those edges had to be decored and backfilled before glass taping around these edges or "chines" as i call them. If you dont you end up with 2 abutting polycore edges which you cannot remove all the air bubbles from when you attempt to glass around that edge. Think about it - often these edges dont fit perfectly, so the panels must be shaved back a bit to get a good fit before glassing together and even the simple process of sanding an edge flush is difficult with polycore as the plastic doesnt sand down easily. If you attempt to grind it - it melts etc. Then your left with this open cell edge which you need to round off so the glass will wrap as you cant glass wrap a sharp edge. But you cant round off open ended cells - you end up with a rough jagged edge which is full of open cells to wrap. So the process my friend used was to decore and back fill after he trimmed panels to fit - then round off the cured bog edge and glue/glass around it. With foam core panels none of these difficulties exist. You can trim it, cut it, rout it, sand it, plane it, grind it, and you can glass around them directly as the foam core itself can be neatly rounded off (usually with a router) and glassed over directly. Using routers was difficult with polycore as the router bits tend to rip out the plastic rather than cut it. Everything about the stuff is just difficult...

Unless you have actually worked with this stuff and seen the entire process of working with various materials in "hands on" detail - its easy to be an ill informed arm chair critic or expert. All i can say is that working with PVC foam cores is so easy due to its uniformity, ease of shaping, cutting and gluing, infusing or laminating. The only bad thing i can say about foam core is - its expensive.

Jorge - a giant mold like that is still too much effort and too expensive. Its feasible for a mast because the surface areas are small and the number of joins in the sheet metal would be minimal as sheet metal in that size comes off a roll and can be as long as your transportation limits dictate. It also wont work below the waterline as you have compound curvature down there. To work with sheet metal surfaces you must have completly simple or "developable" surface curvature only. The topsides to deck line is a compound curved edge aswell. The wing mast however - is all simple curvature in one plane so it will work.

As soon as your working with simple curvature surfaces only - then they can be pulled off the table so why bother with other methods and expense to achieve the same end when you can get repeatable perfect surfaces off the table?

 

Polycore also lacks in stiffness. I have heard much anecdotal evidence from people that have used it about this issue. The guy who build the aft mast Lyra (I'm sure you have heard of him Brian), and the guy who refittied the Hitch Hiker "wired" now aft mast "Zenataos". Both of these builders told me that it sags like crazy and needed far more stiffeners than they thought it would. In fact it seemed that the builder of lyra blamed it on the rig being less than great due to the whole boat bending like bannana before sufficient rig tension could be maintained. Not exactly engineering specifications, but it does sound like you would need a lot more of it to maintain stiffness compared to other materials commonly used.

Maybe if finished panels can be sourced cheap enough it might be good for smaller panels inside the boat away from water.

 

I dont understand where this comes from Barra?

Just about every major boat hull manufacturer across the globe now infuses their hulls in a single shot - including riveria here in australia. The majority use gelcoat and either PE or VE resins. Are you suggesting that they all suffer print through issues and they all have to paint their boats? Rubbish...

 

How many mm of material of little to no structural value is needed to prevent the print through? I can't speak for the aforementioned manufactures, but I have noticed print through on many prod boats.

 

the way i have dealt with it in a past life was to apply a 200gsm veil layer over the gelcoat before vac bagging the rest of the sandwich on top of it. This was using VE resin to make kiteboards. I didnt get any print whatsoever.

I used a similar method without the gelcoat to get a clear carbon finish with no pinholes. Instead of putting down gelcoat, i hand layed a 200gsm eglass woven onto the mold using unwaxed PE resin, work out all the air bubbles and let cure. Then put down the carbon fabric and other foam sandwich on top using VE and vac bag. Voila - perfect pinhole free clear carbon look boards...

 

Yeah, forming the roof in one shot, it's too much work and there are other complications besides that.

Been thinking about it and I believe what I am going to do is go ahead and make the hull molds more permanent. Throw a layer of glass down and get a few guys to do the fairing and sanding. It actually makes the sheathing a bit easier, don't have to be as precise. )

I'l beef up each hull mold up and build them on skids so they can be hoisted out of the way. Same with the bridge deck, that is probably around 14 x 25 ... that is gonna be one sweet deck and one hell of a solar roof!

On the outboard mounting, instead of modifying the hull what about building a bracket (center nacelle) that extends down slightly under the bridgedeck and using a portabracket (21" vertical movement) to get the motors down to where they need to be?

 

sure thing jorge - knock yourself out with all kinds of expensive gadgetry However 1 thing you dont want when your in the middle of nowhere is stuff that breaks down... im sure it could be managed manually if it went wrong but one thing you really need to keep an eye on is keeping costs down. All stuff like this adds up. The guy building the pacific 40 will owe him the best part of $400k when its done - and he spent 5 years of his life doing it. In hindsight - id just buy a damn boat for $400k and start living... the only way its worth it (building) is if you can keep the costs down...

 

I just keep thinking what happens to those outboards when its sloppy out and they get slammed by waves )) ... The electrics are submersible for 1 meter and 30 min, the gas ones are going to suffer

 

it never happens mate - you use the long shaft versions. Many boats done like this for years and no problems with drowning motors...

 

Ok sounds good then.

 

Groper. I'm posting from the perspective of a person who has infused around 30 foam cored yacht hulls in a female mould with VE.

Unlike Riveira, laminate was meant to be LIGHT, around 600g stitched on the outside. Hand laminating very light CSM against the Gel , had little effect on print through, 600CSM hand laminated prior to the infusion stack, went some ways to stop one being able to count every contour foam block after cure when the hull was dragged out into the sunlight.

I'm assuming you will also be using light laminates.

Do what you want with my contribution.

 

That explains it - the contour foam in a curved mold ...

This isn't an issue when infusing flat panels with perforated only core... the infusion channels (if used) are on the opposite face of the sheet- you don't put them on the gel coat side...

 

This isn't the same as grooved foam right? In the bottom where it's curved if those channels are facing in they are going to be crimped shut.

I was thinking to face them out or have the core grooved on both sides. Really would like to NOT use flow media and perf release but if needed just in the bottom that would be okay.

 

The way to infuse round bilge shapes is with "double cut" foam. It's knife cut in a tight grid pattern on both sides and where the cuts intersect there is a perforation. There is probably still a risk of print through if using vinyl Ester but I would use a much heavier laminate for the below waterline exterior laminate anyway for grounding toughness.

 

Dear Groper and Redreuben,
I didn't want to take this subject thread off on a big tangent about the 'nidacore' subject, so I have copied some of our discussions here, and put it on another subject thread dealing more specifically with that subject matter.
(I still have questions on this matter)

http://www.boatdesign.net/forums/materials/polypropylene-honeycomb-panels-hull-construction-31600.html

Cheers, Brian