In search of the prefect Proa

[bearflag]

Remember not to ditch all of your sawdust right away, you can use it mixed with epoxy for all your bevels and filling gaps etc etc.

 

[Inquisitor]

Total Hours: 34.5

Sawdust - Got it in two grades... denser Cyprus and lighter Fir. Besides... I think there is more saw dust than boat.

A little progress tonight:

Tolerances - I'm about to get anal rententive about the tolerances on the alignment. What would be considered accepatable in a production boat? I'm not expecting to make a show room finish, but I don't want it to look like a B&B special. I've got a laser to help me align it, but I'm still in the eye ball range. I think its at least a quarter inch out of alignment in the 60 feet. I also seem to have a valley in my basement floor in the middle. Need to shim up the center six to eight stations a good quarter inch or so.

 

[bearflag]

Progress?

Is there any?

 

[ThomD]

As you know, tolerances and finish are two different things.

1/4" over 60 feet is pretty good, but not so good on the initial set up. You are past this step at this point, and haven't laid out a 60 footer, but I start mold set-up with a chalk line. I snap it, an then I lay a dry line over it. I go to each station mark and make any adjustments from sighting the line. I laid out a 20 footer earlier this year, and I snapped the line is was very consistent about 2 mm out in the middle and each station on the way back had a consistent set off. So I had the bottom within a pencil line in a few minutes. I did something similar with the tops of the station molds, and I would expect the molds to be pretty accurate.

But there are a lot of other sources of inaccuracy. When building over male molds, there can be variances in strip thickness due to angles that are fairly large, there can be build differences in glass, and all sorts of changes might take place after the boat is removed from the molds. In production these distinctions can accumulate due to the nature of molding, and the resulting parts are still seen to be good so a certain amount of error is likely at the best of times.

 

[Inquisitor]

Progress and Tolerance

Thanks for the interest. Also thanks for the "industry" range.

I have made some progress, but very little. I've been on the HarryProa yahoo group quite a bit and am playing around with alternatives. I may even make a short diversion into building a beach cat model so I can test various things that I have concerns about. So the big one is on the back burner... for say a month.

From the last installment, I did a far more accurate lining up of the stations using the laser pointer. I shimmed and checked and shimmed some more... I dare say I'm less than a sixteenth of an inch on the stations along the 60 feet. I've also done about 3 more rows of strips on each side, out from the center.

I understand the variations of the strip and laminate thicknesses, but figure faring will take care of that. My question was related to the "look" of the hull. Last year, I was down at the Miami Boat show and looking at boats in this size, I saw some (looking at the glare down the length) some that looked one nice glare line and others that were wavy and basically looked like crap. I just trying to get a handle on how much starts heading towards the crap side. I know thats subjective... but... couldn't hurt to ask.

 

[Inquisitor]

HarryProa

Oh, I did make one major change...

Its a HarryProa style (sails on leeward hull). Update of pictures will be forth coming... oh... sometime.

 

[ThomD]

With the stuff I am familiar with, wavy is normally problems with fiberglass molding, etc... There is something differential going on, and it comes out in the hulls. Nomally that doesn't happen with strip since it has a firm base of wood which has the advantages of a core, and further longi stiffness of a wood. You can have other stuff that prints through on wood when the boat is older. For instance the difference in areas with a lot of compound near no compound, or only cloth, or some different grain. The less the glass, the less the putty (whole hull foat and sand out), the more the possibility of print through, and doubtless other stuff. It does get more difficult when you build to ultimate light weight.

Fairing won't take care of it, but I know what you mean, you can shave it down at that time, or ignore it since the variance is pretty small.

 

[Inquisitor]

No real progress...

... here. I have temporarily shifted gears and am working on another boat. Please see My Little Mule.