Plastic bag over prop, prevent growth?

[fstbttms]

Originally Posted by AndyEss

An emergency, almost by definition, is something unexpected. Boat fire in the next slip over?

And how far do you think he's going to get with a big plastic bag wrapped around his prop?

[BobFord]

I run Gori props and barnacles can be a very real problem. I stuff Lanolin grease in to the gears , every few weeks and by accident , wiped greasy hands on the prop blade. At next dry out , 6 months , the 'greasy blade', was clean !
I'm now experimenting with a smear of grease on all blades and prop shafts. Previous failures included Propspeed and clear epoxy. In passing - I have not found a satisfactory anti foul paint for aluminium hull. Jotun will give me 6 months but being a cat ,it is not a big deal to dry out .

[AndyEss]

Originally Posted by fstbttms

And how far do you think he's going to get with a big plastic bag wrapped around his prop?

Well, in my own experience trying to scrape a prop clean in 5 ft seas from an approaching hurricane (I had been exploring the mainland with a beautiful new girlfriend, our flight that morning was lucky to have not been canceled) I expect cutting away a plastic bag would have been far faster.

I haven’t tried the bag trick yet, I only bought this boat after retiring several years ago, but it sure sounds from other people that it works quite well. I did the cold galvanizing spray paint trick last haulout, but really have no comparison.
I can’t wait to get off the dry now after 9 unexpected months in the States because of Covid and medical issues.

[Kirie446]

I'm wondering how this would work with a shaft zinc at the end of the shaft. My shaft exits a short stubby skeg and the prop is right there with a cone zinc at the end, no exposed shaft. Since the plastic bag works as an insulator the zinc would be ineffective. Kirie 446

[Russ]

If you're going to get in the water to do this, forget the bag, just smear a thick coat of Desitin (Yeah the baby's bottom cream) on the prop blades. Its high zinc and if you need to move the boat, it'll just wash off. Much easier needs only one dive. Yes, it works.
Russ

[JPA Cate]

Originally Posted by fstbttms

And how far do you think he's going to get with a big plastic bag wrapped around his prop?

Normally, when putting the bag on, you also tie a retrieval line, so that if you need to motor the boat before the hull is cleaned, you don't have a reef basketball instead of a prop. The way we did it, we could remove the bag off the prop from the cockpit.

We used to bag our prop whenever we flew back to the States to see family. It just makes it a bit less work to get ready to go sailing again when you return to the boat. It is not nonsense, nor is it threatening divers' rice bowls.

Not certain of this, but I think the reason it works is because it is a physical barrier to the larval forms of the biofouling organisms, and there were only whatever was there when you applied the bag.

Ann

[Traumagas]

Originally Posted by S/V Illusion

That’s the equivalent of closing the lid on a Petri dish.

Actually Not, The plastic bag Keeps the Fresh nutrient rich Ocean water away from the props, Decreased Light and O2......This method is used in California Marinas in which the Whole boat is pulled into the slip with Isolation Barrier and works Great. Once Boat is pulled int gate just washing your boat and its Run off Changes Ph and Salinity enough to inhibit Growth....

[fstbttms]

Originally Posted by Traumagas

This method is used in California Marinas in which the Whole boat is pulled into the slip with Isolation Barrier and works Great.

I can count on one hand the number of boat bags I have ever seen in use in California. Not to mention they typically want you to add chlorine to the water in make the bag effective.

[mrybas]

Originally Posted by fstbttms

You will be months past needing to have the hull cleaned, so why the concern about the running gear? You will need a diver regardless.

I spent a lot of time on my bottom. Stripped back to glass, faired with a longboard, barrier coated, then coppercoated.
I saw the local diver using metal scrapers. I usually scrub my own bottom once a month with a soft scrubby and a plastic scraper if necessary.

[fstbttms]

Originally Posted by mrybas

I usually scrub my own bottom once a month with a soft scrubby and a plastic scraper if necessary.

After three months, I am confident your soft scrubby and plastic scraper will not be up to the job. Those divers aren't using metal blades because they're lazy.

[mrybas]

Originally Posted by fstbttms

After three months, I am confident your soft scrubby and plastic scraper will not be up to the job. Those divers aren't using metal blades because they're lazy.

Of course they use them because they’re effective. But doubt any of them have spent a couple hounded hours on a bottom job.

[Training Wheels]

Just took the bag off my prop and strut after 4 1/2 months. Prop nice and clean, this is third season we’ve done this in the tropics. Plus, it saves our cutless bearing by not getting growth in it.

It’s been 3 years since we’ve painted the bottom and I still only use a plastic scraper and a light touch with a brush. I do the bottom every 2 to 4 weeks, depending on the season and the growth. Here our main battle is with barnacles; I like to get them off before they get a good grip on the paint.

Our cruising season is starting!

[fstbttms]

Originally Posted by mrybas

Of course they use them because they’re effective. But doubt any of them have spent a couple hounded hours on a bottom job.

You miss the point. The point is your bottom needs frequent cleanings in order to use gentle tools. After three months, gentle tools are not going to cut it.

[nwdiver]

Fill the bag with fresh water, take down attach around the prop, you’re good to go, many in the PNW do this for the winter, pull in the spring and head out....you have to dive to scape the prop and shaft in the spring so diving to remove it isn’t a big deal.

If your antifouling is in good shape in the spring you pull it off and head out....

[Moontide]

Ditto for those who say yes it works. Black is best as it keeps light out. I normally have lots of growth on the outside of the bag and virtually nothing on the inside the times I have done this.


I have heard of some who try to get as much fresh water in the bag as possible with a hose. Guess the theory is to start out with a less organically "rich" environment.