What sanding standard is the balance of perfection and boat-in-the-water?

I'm sanding a PocketShip (and the manual suggests it will need ~6,000 hours).  I'd appreciate builders' wisdom as to the standard for sanding.  I know the goal is a uniform gray surface of sanded epoxy with no divots ot shallow depressions, no runs or ugliness, and no penetration to bare wood.  But I post a couple photos of my working surfaces here:

 

and

If I were to apply Interlux Pre-Kote primer (two coats with sanding in between) followed by Brightsides on the surfaces above, am I making a mistake I'll regret later?   Does each one of these tiny spots (around 1-3 mm) need to be sanded gray?

Thanks,

Mark

 


7 replies:

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RE: What sanding standard is the balance of perfection and boat-in-the-water?

   Beauty is in the eye of the beholder. I've built a NE Dory and a Sectional Shearwater Sport -- with varnish as the finish coat of each one. I have wanted to sand to a uniform gray on each boat, but have never done so. Sanding through to bare wood is a disaster requiring another coat of epoxy (a skim coat, but still). Then I had all that sanding to do again. Frankly, I can live with minor surface imperrfections -- though I applaud those who can do better. 

I'd certainly be satisfied with your second photo.

Advice worth every penny you paid for it.

RE: What sanding standard is the balance of perfection and boat-in-the-water?

   6000 hours = 3 years of 40-hour weeks! I'd never have the patience for that!

RE: What sanding standard is the balance of perfection and boat-in-the-water?

   The small areas of unsanded epoxy will disappear if you use a gray Scotchbrite pad or 000 steel wool on them.  Once you do that, you can apply your primer and all will be well. 

RE: What sanding standard is the balance of perfection and boat-in-the-water?

Mark,

First, I suspect that 6000 hour estimate is a typo. The prototype was completely built, including sanding, in under 600 hours.

Second, perfection is silly. We are all imperfect humans and can never achieve perfection. We can make things look pretty good, but there will always be flaws. They'll just be harder to find.

So, the real question is, how good do you want it? Another way to phrase this is, who are you trying to impress? Decide that and all else will follow automatically.

Regarding your current efforts, you cannot just sand all the divots away. That will lead to sanding through wood in other places. The first sanding effort is to knock down the highest spots and identify the low ones. Once the low spots are identified, put a thin coat of epoxy on them, and no place else. lLet it cure enough to sand and do it again. That way you leave the places that are done alone and only fill the depressions.

In your top photo, you are coming close to sanding into the glass. If it was me, I would not sand any deeper there without adding more epoxy.

Since you are going to paint the boat, you can fill the weave and fair the hull with a fairing compound instead of unthickened epoxy. It's easier to sand and fills the low spots faster than unthickened epoxy. You can make your own by mixing epoxy and phenolic microballoons, or buy a commercially prepared mix. It makes the sanding go much faster.

Sanding for a good finish is actually fairly easy as long as you use the right technique, tools and materials. None of it is expensive (at least no more expensive than epoxy). You can use a manual long board (also known as a fairing board) to get a very smooth and fair surface that the paint will love. The most important thing is the technique.

Good luck,

Laszlo

 

 

RE: What sanding standard is the balance of perfection and boat-in-the-water?

 Hi Laszlo,

Thanks for your comment (and all your other comments on the forum!!).  I recognize the "6,000 hours" is inaccurate, and I suspect it was an attempt at humor in the manual since more than 100% of boatbuilding is sanding.

I've been using Total Boat fairing compound to fill in occasional low spots as you suggest since I plan to paint the hull.  But when I get to these scattered very small low spots as in the photos, I'm wondering if any treatment at all is needed or whether Pre-Kote and paint will adhere satisfactorily.  Far more important than striving for a "perfect" finish is avoding mistakes which will necessitate a re-do down the road.

All the best,

Mark

RE: What sanding standard is the balance of perfection and boat-in-the-water?

   Varnish this thing a keep it bright, I like the blood splatter look. Remember, all good stories fall under the 10% rule -- 10% of any guy's story must contain at least 10% facts, which you already have -  the red spots look like blood splatter and you are building a boat. It's up to you to come up with the rest of the story. 
In all seriousness though, whatever you choose to do will look great :-)

RE: What sanding standard is the balance of perfection and boat-in-the-water?

   Varnish this thing a keep it bright, I like the blood splatter look. Remember, all good stories fall under the 10% rule -- 10% of any guy's story must contain at least 10% facts, which you already have -  the red spots look like blood splatter and you are building a boat. It's up to you to come up with the rest of the story. 
In all seriousness though, whatever you choose to do will look great :-)

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