SPW prop antifouling

[Simi 60]

Originally Posted by fstbttms

Well, I can tell you I’ve seen it used very successfully on many boats much larger than yours. .

Nothing to do with size of vessel but about how fast their prop turns.

But it’s your dime

If only it was 10 cents instead of a few thousand dollars.

[fstbttms]

Originally Posted by Simi 60

Nothing to do with size of vessel but about how fast their prop turns.

I understand that but not only is Propspeed used on mega-yachts but large (sometimes VERY large) commercial vessels who certainly do not spin their wheels faster than you. Just sayin’…

[Simi 60]

Originally Posted by fstbttms

I understand that but not only is Propspeed used on mega-yachts but large (sometimes VERY large) commercial vessels who certainly do not spin their wheels faster than you. Just sayin’…

Most mega yachts, normal yachts, motor cruisers have shaft speeds around 1000 - 1500rpm

Many commercial vessels are high speed, so again, fast shaft speeds

Being an ex working trawler we run a shaft speed of 254 rpm.
Engine runs @ 1150rpm through a 4.52:1 reduction gearbox

Large container ships spin slower than us again but I don't think they would use propspeed but if they did, they also have an advantage of near continual movement doing 10's of thousands of miles more than us each and every year.

[kenbo]

Originally Posted by Jim Cate

I made up some home-brew PropSpeed stuff for trial. Simply hardware store silicone sealant (cheapest brand available) thinned to brushing consistency with epoxy thinner. Painted onto some bits of sheet metal with no primer. flowed out nice and smooth, looks and feels like the real thing and h as lasted several months sitting on a bench. In the long run I was not brave enough to put it on the prop, mostly due to the high cost of slipping to change it out if unsuccessful.

I planned to use a conventional etching primer, followed by a single coat of the goo. May get around to a more conclusive test some day... like maybe on the dinghy o/b, although that prop is painted aluminium rather than bronze.

I find it hard to justify the high price of Propspeed and its offshoots, but perhaps I am missing some important info. Corporate greed seems possibly involved!

Jim

I've been doing what you describe for well over a decade with results comparable to Propspeed in the same local waters. However, I don't use the type of silicone caulk that uses the acetoxy cure (acetic acid smell). I use a neutral cure epoxy like GE Silicone 2 or Lexel. Dissolved in lacquer thinner to a medium-thick brushable liquid and apply over a self-etching primer. As in any painting/coating process prep is key so the prop should be clean, sanded lightly with 80-100 grit and degreased. My typical shaft speeds are between 850-950 rpm. Very pleased with the results.

[Jim Cate]

Originally Posted by kenbo

I've been doing what you describe for well over a decade with results comparable to Propspeed in the same local waters. However, I don't use the type of silicone caulk that uses the acetoxy cure (acetic acid smell). I use a neutral cure epoxy like GE Silicone 2 or Lexel. Dissolved in lacquer thinner to a medium-thick brushable liquid and apply over a self-etching primer. As in any painting/coating process prep is key so the prop should be clean, sanded lightly with 80-100 grit and degreased. My typical shaft speeds are between 850-950 rpm. Very pleased with the results.

Thanks for that report! Very encouraging indeed. I did use a non-acetic type of silicone sealant.

How well did your formulation last in use... ie, before degrading or coming off the prop? And did it maintain it's ability to shed hard growth either through spinning in use or manual cleaning in the water?

And finally, what primer did you use?

I salute your bravery and willingness to experiment!

Jim

[Fore and Aft]

Jim, I have seen a guy use thinners and silicone to make his own prop speed. He polished the prop and slapped it on. A few weeks later I noticed his boat back on the slip and getting prop speed applied. Apparently, the silicone just fell off the prop when being used.
Simi 60 my mate has a boat in Tin Can Bay with a slow revving Gardner diesel, and he uses prop speed. Every time he comes out his three-blade prop is fairly clean.
Cheers

[Jim Cate]

im, I have seen a guy use thinners and silicone to make his own prop speed. He polished the prop and slapped it on. A few weeks later I noticed his boat back on the slip and getting prop speed applied. Apparently, the silicone just fell off the prop when being used.

If he applied it over bare and polished bronze I'm not surprised that it failed. The primer is crucial to the system's performance... that's why I asked Kenbo which primer he successfully used.

Jim

[kenbo]

Originally Posted by Jim Cate

Thanks for that report! Very encouraging indeed. I did use a non-acetic type of silicone sealant.

How well did your formulation last in use... ie, before degrading or coming off the prop? And did it maintain it's ability to shed hard growth either through spinning in use or manual cleaning in the water?

And finally, what primer did you use?

I salute your bravery and willingness to experiment!

Jim

I sail in New England so the boat is on the hard for 5 months every year. So in a 7-month season it lasts very well, very little hard growth and no soft growth. I believe it could last for more than one year but I don't have that as experienced-based fact.

I sail off a mooring so low hours on the running gear, usually under 70-80 hours and I never have to dive on the prop to scrape. I have a Nibral fixed 3 blade that I let freewheel

I don't know if spinning sheds the growth or the critters just can't get a good enough hold to start off but at the end of the season the few that are there usually flick right off with a putty knife.

I buy one part acid-based self-etching, brush-on primer from an auto body supply shop. Small tin because it has a shelf life and I never use it all before it expires. Any brand that they have in stock at the moment that is used for non-epoxy based paints.

I hope that helps.

[Jim Cate]

^^^^
Thanks very much for the info.

Jim

[Simi 60]

Originally Posted by Fore and Aft

.
Simi 60 my mate has a boat in Tin Can Bay with a slow revving Gardner diesel, and he uses prop speed. Every time he comes out his three-blade prop is fairly clean.
Cheers

But fairly clean is what we have now, had a look yesterday, not bad enough to warrant giving it a scrape yet and we launched in Feb.
Admittedly, it did have antifoul and epoxy primer on for at least some of that time

Based on previous years i'll have to give it a scrape 3 times in the next 8mths before we come out of the water again
Each scrape takes about an hour on hookah

Is 3 hours on hookah worth the not insignificant cost of getting a 48 inch 4 blade prop and barn door sized rudder prepped primed and painted with propspeed?
I'm not convinced it is.

Different story on small props
On them I'd definitely use it.
Far less labour hours, far less product