F85SR Concept Boat

The second coat of hi build has been applied.

So far all up I've sprayed 8.5 litres of hi build primer over 2 coats and spent 18 hours wet sanding.
Up close the hi build is now so thin it is almost translucent and the shop floor is covered in white powder.
It did screw with my head just a little, all that money and time to put the primer on
just to spend a lot more time to rub it off. However the hull is now nice and smooth and fair.
Next is to spend some time cleaning up the mess so I can apply the top coat.

That is incredible work, thank you for sharing.

But, seeing all the effort going in to this build, I feel better that I bought a factory boat... there is no way on earth I have the skills/time/space needed for this level of construction...

Jay,
Thank you for your comments.
Unless one really enjoys building and I mean really enjoy building boats, then buying a factory boat is a very smart move.

I really enjoy building but this is the last boat that I will build (due to my ever increasing sensitivity to resins) so I'm taking my time.

I have been waiting for the weather to clear up so I could spray the top coat on the main hull.
Finally after a week it all came together and it now has the top coat.

An interesting bit of trivia- To spray two pack polyurethane one should have a relative humidity of less than 85% and at least 3 deg C between the Ambient Temp of the surface one is spraying and the Dew Point Temp. This is because when the paint hits the surface the evaporation of the thinners cools the surface by around 3 deg C. If the surface temp goes below the Dew Point Temp moisture will settle on the surface and this moisture will affect the hardener in the paint. The drop in surface temp is the same as if you get acetone on your hands. It makes your hand cold because its evaporation is fueled by energy it takes from your hand thus making it colder. The same thing happens when you spray paint. I had to wait a week for a wet spell to pass and finally ended up with a relative humidity of 58% and Ambient Temp 8deg C above the Dew Point.

Ultimately I would like to qualify for Cat 2 coastal racing. From what I can make out to meet the safety regs I will need a bright colour with a min area of 1m2 that can be seen when the boat is upside down. The boat would be rather slow upside down for that and several other reasons I hope that I never find myself in that position. Given that I will be keeping the boat at home under cover rather than on a mooring I have decided that I will not anti foul the bottom so I thought this may do the job. It has an area of just over 1m2. I will also paint the lower section of the dagger board with this colour.

I think I happen to have enough surplus materials to make a cradle for the main hull so thought I'd just give it a go.

First I covered the hull with 3 layers of plastic and one layer of vacuum film. I don't want to damage the paint.
Then 2 layers of a fairly heavy triaxial glass. I was given a couple rolls of this stuff a few years back along with some really out of date epoxy.
But it is only a cradle- wouldn't use the ood epoxy in the boat itself.

I also happen to have several sheets of 3.5mm pacific maple marine ply. So here s a couple of pics of the work to date.

The ribs will be trimmed back by up to 6 inched each side and there is more timber to be glued in place length ways along the keel and sides to make more of a frame.
The timber will be acting as a high density core and it will all have at least 2 layers of the triaxial glass over it.
Frames will also go under the ribs and be bolted to gal angle that is then bolted to the trailer.

Hint for people looking to copy Phill's idea here. If you don't have Phill's experience be really careful. I've seen people get carried away building cradles throw too much glass on in one go and generate so much heat that they damage the boat's foam core. Like anything lamination wise, take your time a do just a few layers at a time.

Scarecrow, Interesting that you mention that, a very good point. I had this originally planned with some friends coming around to help. When I found out the forecast temp was going to be 37 deg C I became concerned re thermal runnaway and I put it off until I got a day in the low 20s. Then still used slow hardener and only 2 layers of glass. Once the frame is built around this skin I'll do a bit more possibly with a 5mm core cell as core, I have a heap of this 5mm M80 foam. I have no other immediate use for it, picked it up super cheap many years ago.

I haven't been able to touch the boat for the last week and it looks like it will be a few more weeks before I can get back to the boat. I did get to snap a couple of pics of where I'm up to earlier this arvo.

I got out my laser level to mark the frames so they can be trimmed and all support the boat evenly when on the trailer. I have a couple pics below. One time exposure showing the laser line. Held by hand so no super clear. But then photography was never my strong point.

The cradle will now be lifted off and all the excess timber and glass will be trimmed before all the bare timber is laminated with triax glass & epoxy.

Then the cradle will be lined with marine carpet, the hull set in it and work will commence on the cabin top and windows etc.

The cradle is off the hull and now trimmed.

Starting to look the part, but still needs the timber encased in the triax.

Looks awesome. How does the water drain away from the hull once situated on the cradle?

Jay , good question.
The plan is to have a layer of 3/4 inch rubber 8 inches wide down the centre of the cradle with the rubber and the rest of the cradle covered in marine carpet. Either side of the rubber will be 3/8 inch drain holes every 8 inches.
I do have concerns about the hull discolouring because of water trapped in the carpet and hopefully this will do the trick.

Unable to get much done over the last 5 weeks too busy working on a house building project but still I have a couple of pics below.
To ensure the thickness of the lining of the cradle did not cause a problem I have left some space for expansion.
Once the hull is in it with the lining these gaps will be filled and glassed in place.

The cradle only needed one more layer of triaxial for it to become bullet proof. As I peel plied the glass this took me around 8 hours to laminate. I was happy for that to be behind me.

Before putting the right way up for the rest of the project I thought it prudent to double check that the D/B still fitted without problm. Good thing because I found that fairing compound had gone into the case right at D/B the trailing edge. IT was easy to remove in this position and now the D/B is running just right.

I used 1/2 inch thick felt to temporarily line the cradle just because I had it available. It will eventually be used to make cases for the rudder and D/B.

Once in the cradle Mark came around with some templates he cut for me on his CNC machine when he cut my windows. The templates were to make a 6mm rebate so the windows will be flush when fitted. I made the cabin side 16mm thick to allow for this. I'll vacuum 3 layers of 200gm glass around the edge before the hole for the window is cut.

Those windows will look amazing! I was surprised to see the deck un-painted with the hull looking completely finished. It much be easy for you to

switch gears

in your shop. I have to completely finish the work and fairing before making a large transformation of the shop to a paint booth.

F-25c,
For me this approach should be the easiest way and give me the best result. A simple plastic shirt taped just under the gunwale net tube should eliminate any over spray.
The top is even more straight and fair than the hull so I just need to fair in the taping. (the way I do it is very quick and easy.)
Once the shop is tidy changing it into a spray booth takes around 5 mins.

This might work for me too. How do you vent out the overspray? I have a HVLP turbine system but still get some mist in the air if I don't have air flow. I can still see the part but not as well as I'd like without airflow. I have a positive air mask. How will you paint the deck, hang sheeting from above, turn upside down, or move the boat outside?

F-25c,
I'll just tell you what I did and see if it is of any use.
One end on the shop is open. I set the boat upside down supported by bricks under the beam landings so I could take down my winching system as it would get in the way.
I put planks on milk creates down both sides of the hull. This enabled me reach far enough to spray from the keel to the waterline on each side.
I did 3 passes. Alternating from side to side, always spraying from the back of the shop to 7ft x 8ft opening.
Then I took the planks away and 3 passes from the gunwale to the waterline. Same again. A friend came around and mixed while I sprayed in an effort to keep a wet edge. I expected to get over spray from the waterline to the keel but that didn't happen. The 2 pack paint I'm using stayed wet enough to absorb the over spray.
I had a 13cfm compressor driving my positive pressure full face mask and a 15cfm on the HPLV gun. When I undercoated I only used the 13cfm on both and I had to stop intermittently for the compressor to catch up.

I also have a very large fan that I could have used to help vent the shop had it been necessary.

That worked for me.
Hope it helps.

If you have too much mist in the air look at you pressure at the gun. Too much could do that. I did not have that problem. Overspray on the hull now will be avoided by taping plastic sheeting from just under the gunwale down to the cradle the hull is in. I have a heap of cheap plastic sheeting left over from when I made the cradle and it will only take a couple mins to tape in place.
This has all worked great for me with the paint I have chosen to use.

Thanks for the write up. Thats a nice looking cradle.

Another step closer.
I still have to paint on the non skid. I'm going to use light grey Kiwi Grip. Then I can pernamently bolt on the fittings.

I pulled the floats out from under the front verandah and started rubbing off the guide coat to ready them for top coating.
I top coated the beams yesterday, they are in the background.
Not long now and should start putting the pieces together.

Top coated the floats a couple days back.

Then took the cradle out and glued in foam to give the main hull a soft ride.

And last thing today managed to paint the non kid onto the main hull.

Come on Phill hurry up and post some pics of the luverly windows in the sunshine.

Was looking good last night in the car park.

Looking good <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" />

Hey Phill you know what would look really good?.....

Black folding struts! ;P

OK only 6 more I told you so's to go <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" />

The floats are now on. Just need the rain to stop so the taping and fairing can be finished.

Looks good Phil.
It should win a few looks good in the carpark awards
Richard

Richard,
Thanks.

Glass taping the front beam on the inside is a real challenge as the foil cases are in the way.
A friend offerred to climb inside the float and work around the foil case to do the job.
That was a good thing because I just don't bend like that anymore. Here is a couple of pics.