efficient 10m displacement powercat (build thread)

[groper]

And so it has begun...



These are the first 2 peices of this boat to be infused;

They are 2 of the webs in the forward beam which will also form the sides to the anchor locker etc...

All bulkheads and beams have been cut out of the airex foam sheets via CNC router from the CAD drawings, the files sent to the local CNC guy look like this;

Ive put together the mold for the hull "shoes" and this will be an interesting experiment to see how well a direct female mold for infusion works... its built very lightly out of 3mm foamed PVC as an inside former, with a skin coat of glass/epoxy to seal up the joins and staples etc... i have no idea how well its going to work with infusion, could be a complete disaster and destroy itself or a surprising success!

Here is an updated rendering of the boat as ive made a few changes prior to finally making up my mind

The weather is absolutely atrocious these last few days, so i cant do anything outside, but I will be gradually getting thru things over the next few months when the weather improves... just doing some more small infusions to get a better feel for how things work, then ill go for those hull shoes! So far so good... happy days

(note: thread discussing the design is located in the Design Forum at http://www.boatdesign.net/forums/boat-design/efficient-10m-displacement-powercat-44519.html)

 

[harry cassin]

Looks fantastic, hope to see many more photo's

 

[groper]

Busy infusing bulkheads lately... ive worked out that its quicker and easier to hand laminate small panels, its only worth infusing the larger panels IMHO... so im planning the infusions to be as large as possible from now on...

So heres a few pics;

This is a few peices i hand laminated on the table;

Heres a pic showing how im doing the cutout reinforcement in the bulkheads. The cutout is routed out of the foam core, then fill the bottom of the channel with thickened epoxy and let it setup. Then wetout some 1000gsm UNI tape, fold it up and push it into the channel and finish it flush with some more thickened epoxy. Once its all cured, i infused the top and bottom skins over this, and trim it back to the solid UNI edge once cured. You could do all manner of cutouts like this, windows, doorways etc...

And this is the end of the infusion of one of the beam bulkheads including the shear web reinforcement, aswell as the 6mm x 100mm thick solid UNI top and bottom caps rebated into the foam and infused in 1 shot after the cutout reinforcement. This panel is 5m beam * 2.2m depth to give an idea of size and weighs 38 kilograms + whatever paint goes on later. Will do another one of these tomorrow if all goes to plan

Happy days...

 

[groper]

just keeping things up to date and bringing in some pics from my other threads etc...

Most bulkheads and beams are done and stacked away behind the house, all infused flat on the table... ive been working on the hull shoes at the moment. The aft half of the shoes had only single curvature, so these panels were infused flat on the table in 1 piece, then bent into shape with the aid of softening the green resin in the sun. I then wrapped ratchet straps around them to pull it together and hold the shape, then reinforced on the inside along the bent edges to lock it into shape.

I tried both methods, leaving the core out where the bend happens then adding coremat afterward to stiffen back up. And leaving the core intact and kerf cutting 1 side where the bend needs to be - i found the second option the most desireable... its lighter, uses less resin ($$$) secondary laminating the coremat (which also takes time), is cheaper (no coremat and less resin) and less hassle cutting and tapering the core when setting up the infusion etc... only down side is making a bit of glass dust when cutting - which can be avoided by leaving the glass off 1 side in this area anyway... both methods do not require fairing afterwards, although very slight chines are visible on the kerf cut panel as opposed to a smooth curve with the other method.

The front half of the hull shoe has compound curvature and i didnt like the idea of strip planking etc, so i infused it in a make shift female mold to form the shape and i will fair out the 'whoops' from the mold afterwards.

I need to join the 2 halves together now, then fair out the join and the front half...

 

[groper]

oh, and i had to make a boat shed today also, as ive outgrown my little garage now the hulls are to be joined @ 10.6m long...

so, some star pickets banged into the ground, some 50mm electrical conduit and the biggest tarp i could find... its all cyclone rated of course...

 

[Mr Efficiency]

You have a deeply submerged transom there Groper, with flat buttocks aft ?

 

[Frosty]

Glad to see you designing you own cat, i wish i had enough knowledge to be able to work cad etc, I was going to do a 50 foot simpson some years ago and thought on it for 6 months and came to the realisation that it's a huge commitment.

Your not kidding it is. Just go an look for an old ferry or a fishing cat thats been used on the reef. Dont worry about work ,that alone will be plenty and will be sufficient to complete your gratification.

It will be what I do next Ile tell yer, buy something working and running with performance that you want and have seen.

 

[FMS]

If you need a boat that's the easy way to go with today's market.
However with great risk comes great reward.

 

[Frosty]

If you need a boat that's the easy way to go with today's market.
However with great risk comes great reward.

With great risk--can-- come great reward, you can also get your pants pulled down wich is highly likely where risk is involved.

Why take risk when it possible to achieve the target with little or no risk

 

[FMS]

It's a different target.

 

[Frosty]

I was basically replying to Harry's post.

 

[groper]

You have a deeply submerged transom there Groper, with flat buttocks aft ?

Transom is full depth of hull at max displacement = 400mm.

Operating cruise speed = 20kts, max speed = 28kts

So its a "high speed displacement hull" with good efficiency at the designed cruise speeds in excess of froude number = +1.0 according to the CFD modelling anyways... its not a slow cruiser type of boat, its a fast game fishing type of boat, hence the deep transom stern to avoid excessive squatting or bow up trim...

 

[Mr Efficiency]

Transom is full depth of hull at max displacement = 400mm.

Operating cruise speed = 20kts, max speed = 28kts

So its a "high speed displacement hull" with good efficiency at the designed cruise speeds in excess of froude number = +1.0 according to the CFD modelling anyways... its not a slow cruiser type of boat, its a fast game fishing type of boat, hence the deep transom stern to avoid excessive squatting or bow up trim...

Ok, so you won't be getting great efficiency at trolling speed then ? I hope it comes together the way you anticipate, what engines have you settled on ?

 

[groper]

That's correct, compromise slow speed efficiency for high speed efficiency... However high speeds use a he'll of alot more. At troll speed the difference is small...

Twin 90hp suzukis will power it... 60hp would also do it, but the extra grunt and larger alternators are attractive... Minimal weight penalty etc

 

[Mr Efficiency]

It is the type of boat that interests me most, I will likely be using you as a guinea pig to firm up a few ideas in my own mind about what is the best way to go, so get the damn thing built and give us the results of the sea trials.