arcdude

Almost completed the final coats of paint, coming along nicely except for a few bugs that decided they'd become part of the boat, adds character! Will post some pics before long.

arcdude

Anyone have any idea what the optimum time for curing spray can enamel is for wet sanding and compound, seems to me about 24 hrs may be enough?

Jeremy_H

Hah!, know the bugs one!

Hardness before polishing is a judgment, the timing can vary, even between colours. In essence, so long as it does not pickup and drag when flatting it can be compounded. The more the paint cures the greater it can withstand heat, especially with acrylics which are poor at early stages of cure, so keep the surface cool if compounding early. The harder the paint becomes the harder it is to compound it, but the harder it is the higher the gloss. So I do it in two stages, a leveling flat and polish up to get the surface right, then do it again once the paint has fully cured to a point when firm thumb pressure leaves no mark.

arcdude

Thank you kind sir! I rather like the two stage approach idea, I'll give it a try

arcdude

Well mucked that up In wet sanding the back of the sponson as seen in the pic you can just see the prime coat trying to bust out from under the wonderfully shiny new paint job. Question; can the surface be taped and repainted and can the tape edge be sanded down to hide the repair? In defense this is the first time going through all these steps for a good paint job whereas in the past as with a lot of people spray it, compound it if lucky and off you go. dooohhh

arcdude

I'm smiling again Did a little web search and found a neat little trick used by automotive painters called a soft edge. So I repainted the ends of the sponson's using this method which is taping around the corners and leaving the tape somewhat bent outward around the top edge and sprayed on an angle from behind the tape and presto no visible tape lines, a little buff and away I go

arcdude

Started to paint the graphics, the underside of the shark. What I did was take a cereal box and cut a squiggly line and place it 1/8th inch above the surface and spray on an angle over the cardboard to fog the edges rather than having a built up line to try and hide. Think it gives a more natural appearance anyway. Kinda lookin a little sharkish

Jeremy_H

All sound stuff so far, keep it going.

You're like me, finishing models with unknown performance before proving them. A lot of folk frown at that, but then a lot of folk miss the enjoyment from doing it thing, so I'm with you. Plus performance changes with the weight of paint .

Jeremy_H

Btw arcdude, diverting from your boat if I may. Got hold of a Honda GX31 on the weekend for the trolling OB idea, what a lovely motor. It needs a clutch assy as it came from a water pump so didn't have one. I've decided to look for another with clutch and use this one in an RC boat instead.

arcdude

Excellent find, that'll be a big boat A clutch is a must, I tried it without and was unable to drive the prop down into the water all it wanted to do is act like a paddle wheel. As mentioned the 4 stroke with clutch is definitely the way to go. I did a lot of research prior to building mine and didn't find a lot of info available. There is a lot of people trying to do this and I happened to stumble onto the right combination quite quickly by experimenting. There is hardly a time I go out to the river and someone is trying to buy it off me, not for sale If you like I can forward some pic's to a PM if you like of the mounting and so on.

arcdude

Now that I have the base paint down after a few mishaps in sanding the edges a tad too far and repairing I'm set to do the mouth I've enclosed a pic of the basic idea I'm trying to achieve which is just a basic grey and white scale mouth, somewhat of a simplistic design without looking too much like a cartoon. Curious how to proceed with this, should I grey out the bottom of the mouth and black out the top and then do teeth last, so confusing Trying to tread cautiously here because it's the first time painting graphics, with a spray can no less.

arcdude

Here is a drawing (rough sketch) of the proposed mouth, sure could use a second opinion! The top line of the mouth will be black, the inside grey and the pearly whites white. Not sure what else to do to get a somewhat anatomical likeness in a simple form Straight symmetrical teeth seem to be what is often drawn but I don't think sharks have dentist's

Jeremy_H

A quick go from me

arcdude

That's hilarious, not your drawing, I've been drawing this thing seems like 50 times and have come down to an outside shape very similar to what you've provided. The part I'm stuck on is the teeth, in your drawing the teeth encroach both the top and bottom. However the missing link in my rendering may be the split down the center of the mouth in shading. What I was going to do was make templates top and bottom and paint the black first and when dry mask and do the bottom with the tooth templates on to save on doing the teeth after. Actually it may be a better result looks wise to do the teeth into both sides, rambling I know What process would you suggest?

Jeremy_H

Mask the entire outline of the mouth, and mask off the teeth.
Paint the entire mouth black
When dry mask the gum line leaving the grey area, paint the grey.
When fully dry rub down the mask edges with P800 with the pressure kept on the masking tape. so work from the tape just over the edge, then remove all of the tape.
Flash over the mouth edges with P1200 or 1500, gently. This will knock back the mask ridge left, and cause the black under the grey to slightly breach through at the very edge of the mouth, which will hep to define the grey.

arcdude

Thanks to a kind gentlemen in the UK I now have what may be the final product, Thanks Jeremy_H I drew the outline close to what you provided, (no printer) it was certainly better than what I had scribbled all day today, cheers m8

arcdude

I didn't realize the tape could be sanded down with the edge of the paint, interesting and I'll give it a go

Jeremy_H

Cool, that works. The aim is to capture that sort of snarling look with the jaw line, which you've got there.

Imagining the grey/teeth contrast being bolder in the final think it do it methinks

I-fly-any-and-all

My Feedback: (1)

That is a nicely built boat and your design intrigues me. Not too long ago I went to a hobby expo and bought what I believe is a late 1940's or 1950's air boat with 4 blade wood prop powered by a ohllson and rice .60 side port ignition engine. Can't find much info on it other than believe it to be called a tether boat, man I'd love to see it race! Recently traded it to a long time friend for a Royal Stinson Reliant airplane.

arcdude

Thank you for the compliments and support in doing something a little different, positive feedback is always nice when venturing down an unknown path As you may have noticed throughout the thread there has been a constant evolution in design and redesign and how it works out in the end I can only hope for success and if the experiment works there is enough information posted to enable someone else to give it a try, at least that is part of the intent on posting this creation.

I have read some information on tether boats and the speeds are incredible, were you able to give it a try before giving it away?
Cheers,

Jeremy_H

A new member joined our club last week, he's retired into the area. He's a former record holder for one of the tethered hydro classes, he showed me some custom props, incredible things. I think he said his record was 128 mph.

With the mouth painting thing I'd practice it. Spray light with well warmed cans. The flatting of the masking edges stops the ridge that's left behind being too much higher than the paint that's just been applied, it reduces the risk of breaching surrounding paint when bringing a high ridge down. In principle, if you flat through the paint to reveal the tape edge then you know you're there, but best to do that with firm rubbing blocks, I use steel ones to ensure there's little chance of the paper curving over the edge and eroding the newly applied paint.

arcdude

Appreciate the tips m8 a big help for sure. I've already done some practicing today and will do a little more before I attempt it on the boat, I'd hate to have to redo what has come out good so far. Also I do happen to have a hard rubber sanding block that's never been used, gotta get it dirty sometime. This boat is sure a lot of firsts in different methods I've not done before

Jeremy_H

Couldn't resist

arcdude

Couldn't resist huh! made yourself a nice hub I see Is that the correct prop? looks to be about a 16"-18" or so. Have you had it running, Honda gonna run forever. What is the weight of that motor looks heavy and what is your plan for it?

I-fly-any-and-all

My Feedback: (1)

I wasn't aware my pictures didn't show up so for your enjoyment here is the old tether boat, I wasn't able to try her out before trading it but I sure did have plans to. The guy who has it now is a long time friend, I'm sure one day I'll have it in my possession again!