Cordless polishing of a GRP hull

Greenheart

Greenheart

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I bought a corded Silverline rotary polisher two years ago for under £30, and it has been a huge success. It's great for sanding too, and plenty of places sell the hook & loop sanding pads inexpensively in different grades.

But now the boat isn't in the shed anymore, and I don't have 150m of extension cable, or any 240v access.

I do have a seemingly tireless 18v Bosch cordless drill. If I find an M12 bolt (possibly M13, it's massive) to attach the Silverline's circular pad to the drill's chuck, is the Bosch's higher gear likely to give enough speed to polish the hull?

I don't fancy buying a cacophonous 2-stroke generator for the polisher, I'd rather spend the same money on one of Bosch's 6 Ah batteries (present one is 4Ah)...but only if the drill's turning speed is adequate to polish the hull.
 
I think you will need more than one 6AH battery to polish a boat's hull unless you plan to have quite a few breaks whilst the single battery recharges. I think you will also find a cordless drill quite hard going physically compared to a rotary polisher.
 
I think there's a reasonable chance it will work, You don't really want to turn the mop at high speed. I've used a corded drill in the way you describe and need to run it at about half speed. I think you may find it's an M14 bolt you need. You need to trim it down to fit into your chuck.
 
Thanks for these, I'll check the drive-diameter and try it out.

It isn't a big hull. And it's dry-sailed, so no need to scrape off barnacles or old anti-fouling.

It's just a bit rough and dull, compared to two years ago, when I last gave it a thorough buffing.
 
I used a Makita cordless on mine last week. It took four sessions of 30-40 minutes per battery charge for a 33-footer. The 30- year-old hull looks better than it did, but I wouldn't call it a great finish. Easy job, though.
 
Yeah, hiring is a smart answer. I'd been resisting getting a generator. As it is, they're often for sale at Lidl between the carrots and the badminton sets. But it might easily be another one-season wonder, another thing to take to the dump in six months.
 
A drill runs too fast to polish or compound.

The only cordless polisher I am aware of is a Millwaukee, I think you would need 2 batteries, unless you fancy a break each time you need to recharge. I think the cost of the polisher, batteries and charger will be expensive. I have no idea of a product review, but their corded polishers are considered to be class leading.
 
Hmm, my hope was to accomplish a not-very-demanding polish, using mainly the things I already have.

The cordless aspect of the question, means that overly-high drill speeds aren't a problem...

...if anything, I was concerned that my 18v Bosch might not turn fast enough.
 
Do it by hand, it works better in my experience, tho obviously difficult on a large hull.

I spent a long time power polishing my hull this winter. Having got into a discussion about the merits of my Father's cutting compound, bought cheaply in about 1973 and expensive 3m stuff we hand polished two tiny areas of the boat. Those two areas still stand out against the rest, being shinier and having better colour saturation.
 
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alahol2 said:
I think you may find it's an M14 bolt you need. You need to trim it down to fit into your chuck.
Click to expand...

Quite right, sir. Matter of fact I was so sure you were right, I ordered an M14 without first looking at the Silverline fitting.

The Bosch cordless certainly takes a rather smaller maximum diameter bit...I had assumed you meant I'd need to cut off the hex-head, but as I'm sure you knew, I'll also need to sand off all the thread at the end that fits in the chuck. :rolleyes:
 
I have just invented a cordless polisher.

It comprises a job lot of plastic ducks, some sticks, glue, rags, string, and, of course, polishing compound. A stick is glued in a vertical position on the back of each duck, and some rags tied round each stick at the same height then dipped in the polishing compound. The ducks are then tied end to end in a continuous line around the waterline of the floating hull.

Wave action will polish a band around the hull without any effort required on the owner's part. When it is polished to a satisfactory finish, the rags are adjusted up or down, as required, and more polishing compound applied. This is repeated until the whole height of the hull is done.

Patent applied for. 10% discount for YBW forumites on the detailed plans and licence package.

Form an orderly queue. Make payments payable to my new Cayman Islands account.:D
 
Hmm, thanks for that Andy, but I refuse to buy any tool which, alone, costs more than my whole boat did!

I beheaded the M14 bolt and sanded the end slim enough to fit in the Bosch's chuck...

Screenshot_2018-03-16-15-57-15_zpsdoywzqei.png


...so now the polishing pad can be used without the Silverline tool it was intended for...

Screenshot_2018-03-16-16-13-28_zpsu9fpaf6w.png


...although whether the Bosch will spin the polishing pad fast enough to do a better job than I can by hand, remains to be seen.
 
Does the long silence indicate that it didnt go as planned?
Or the boat is sooo well polished and shiney that its mesmerising??
Sorry. I just ask because i have a hull with a few small scratchs .... and was wondering how this worked out?
Thanks
 
Yes it's an old thread, but provides information to continue with the discussion.
When your old 12-18v cordless is failing take a 10m length of cable, place bared ends on battery terminals and insert battery. Connect other end to boats 12v and away you go!
I did it to a 18v angle grinder and it ran as fast as it ever did with the 18v battery.
I borrowed a polisher to remove masses of scratches on my 4x4 that had been offroaded intensively. I found 350 rpm worked best for me as any faster ran the risk of damaging the paint (result was fantastic)
 
Polishing by hand would be good lockdown exercise.
I did my Laser in a long afternoon, starting with 400 w&d and finishing with Farecla G10.
 
Thanks for reviving an old question that I had entirely forgotten I'd asked.

I think my 2018 sailing season began with me working for five weeks in London; then a variety of other issues put the polishing question in the shadows, where it has remained since.

Meanwhile, the facility for using the 8" disc on the drill with a sanding pad rather than the polishing mop, has been extremely handy.

And at home, with a sanding pad on the corded polisher (resting upside down on its flat handle, with the on-switch operated by a careful toe) I've been able to sand even quite arduous and ambitious woodworking jobs, holding the piece in both hands with the Silverline stationary on the ground.

49816721221_a091b4e350_w.jpg


What, that? Oh no, that's been in the living room for years. I need a sit-down after sanding the tips of my oars. ;)
 
It's easy to forget the old threads...seems like you've had quite a few goid adventures with the sanding disc since! :)
Did you ever manage to get a chance to try it polishing the hull?
LW - was thinking if a hand polish but there are a few nasty scrapes so i was going to fill them and then try 3M medium compound and wax.
Really not sure if thats the right choice. Have tried a few searches to see if theres much info or experience of the 3m Medium and Wax but can't find much.
 
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