How to minimise fouling on a yacht to be left in a village lagoon for 6+months?

[dwp2020]

Greetings! My first post here to this amazing information resource I’ve been reading for a while now. Please forgive any mistakes in my forum etiquette 😊

It’s an antifouling maintenance (or actually a no / poor antifouling maintenance) question for you all. I could not find anything focussed enough in my search of the forums on this yet, but did see the sticky on barnacle removal today, which prompted me to post.

My son has an Endurance 35 in the Mentawi Islands of Indonesia. He has to leave it next month for 6-8 months anchored in a village lagoon, with paid monitoring to a person or family there planned for while he is away.
He says there are no places in this remote area or within a week or so sailing that he can have it brought out and stored on the hard, so I have two related questions:
1. What would be the best way to minimise the fouling that will occur?
2. This one is likely well-discussed out there…. what are the best ways to “unfoul” the hull when he returns? A link to existing posts / information on this would be fine for now.
(I don’t know the recency of his last antifoul but I have to assume on his budget it’s been a while back, and he has been manually hull-cleaning in the water every now and then as he travels around)

Cheers, and thanks.

[chrisr]

RE 1. short of arranging a boat bag (which likely not possible in this location), i really don't think there is much you can do.
as regards the bag, depending on time and resources available perhaps it is possible to manufacture something that will function well enough - but this won't be easy
if you can make something, then it's a case of getting some pool chlorine for the locals to add every week or so

RE 2. hire a diver with a scrapper !

cheers,

[JPA Cate]

Hello, there, dwp2020,

He should bag the prop. If he does that, it limits the growth on the prop, which he will want to move the boat. He should clean the prop well first. A plain big plastic bag will do. He should tie a line from one corner of the bag to something on the boat, so that he can remove the bag without having to get in the water (he could be in a hurry to move the boat.

What he should expect when he gets back is thick bouillabaisse, a mixture of corals, barnacles, shrimp larvae (that craw inside your swim trunks, and bite you.) We used 4" putty knives to scrape this sort of stuff off. Old credit cards are somewhat softer. He should consider that the paint that is on it now is "finished"; it will not renew.

The best thing is if he has a friend who can scrub it for him once a week. Whatever he can arrange in the way of that will help. However, the story with hull biofouling, ime, is that first slime gets on the hull, and then things come along that attach through the slime into the paint. Next, are tubeworm and flat corals, and now anybody else who wants a new home or stuff to eat gets on board, too. So your son should expect a yucky mess, and the boat unable to move out of her tracks if it is not kept clean.

Ann

[dwp2020]

Thankyou Ann and ChrisR, very helpful info for me to pass on now.
David

[kapnd]

Bagging the hull with chlorine tabs is NOT at all eco friendly, and possibly illegal in many locations. The bag will almost certainly leak, and will most definitely get dumped when removed.
Chlorine is extremely destructive to coral and other marine life, so if you care about the possibility of your grandchildren someday enjoying the same beauty that you see today, please don’t do that!

[dwp2020]

Kapnd, Thanks for your input on this.

I had not heard of this option till it was raised here.

I'm with you, it does not look like something good for the local waters and environment, and in a remote and uncontrolled setting it's hard to imagine it working out well anyway. Which Chrisr sort-of implied. His second manual option seems to be the way it must go on return.

Apparently one can use the suction handles used to carry/control large sheets of glass to give you a solid point on the hull to hold against, as you scrape around and build up your arm muscles...

[JPA Cate]

dwp2020,

He's going to return to about 6" thick biofouling over the whole hull, there won't be a spot for the suction handle at first. It is going to be really nasty if he can't arrange to have it cleaned while sitting there. It is a warm, nutritious soup, and will grow a great deal of "reef community". Your son is kidding himself it won't be so bad, but he is setting himself up for an unpleasant, dirty job.

Ann

[dwp2020]

Indeed Ann!
It's a really unpleasant and frustrating in-water job if anything hard gets attached, especially barnacles etc. I reckon a small weekly wage that supports a local teenager will be far less than the time and cost involved in what would otherwise be needed 6 months from now!
As a marine zoologist by training way back, do I detect some knowledge and/or passion in that area of marine fouling communities? Or is it a "been there done that" life experience talking

[JPA Cate]

No formal marine biologist education, but have helped scrape our boats' bottoms for the last roughly 45 yrs., prior to re- anti-fouling.

Ann

[wingssail]

Mentawi Islands! Wow, what a beautiful place but a tough one to leave a boat (no services).

I think a monthly scrub/scrape will keep the bottom fairly clean. I'd use a 4" putty knife, or some other form of scraper. A person with fins and a snorkle can probably do it in abour 4 hours, maybe spread over two days. It could be a decent employment for a local in those villages.

Photos:
Mentawi Islands surfing
Back sides, beautiful

[jtsailjt]

I realize that in some areas the speed that fouling happens is much faster than in others but I can’t imagine anyplace being so bad that weekly scrubbing of the bottom is necessary unless current bottom paint has completely failed. In areas of bad fouling I think if he hired a diver to scrape/scrub it about every 2 or 3 months that should be sufficient to keep hard growth from occurring but local boaters in the immediate area could probably advise him about timing the best.

I’ve used a 12” wallpaper taping knife for open areas and a putty knife as well as a coarse scotchbrite pad with a hard backing and a handle for more curvy areas and the propeller. It’s surprisingly hard work but a good diver should be able to do a decent job of keeping the bottom clear using one tank of air on a 35’ boat about every 2 or 3 months and then plan to have it hauled, pressure washed, and repainted and zincs replaced soon after his return to the boat. But I do think he’ll save himself a lot of grief by arranging that it be scrubbed/scraped a few times during his absence rather than letting it go the whole 6-8 months and then trying to deal with it.

[wingssail]

What we need to recognize to answer the OP's question is that the Mentawi Islands are a very remote place in an undeveloped area of
Indonesia. The advice has to be tailored for what is available.

From my experience there I'd say:

Originally Posted by jtsailjt

...I think if he hired a diver...No divers, no air ...
...local boaters in the immediate area ...See photo...
...12” wallpaper taping knife.No Ace Hardware there
...coarse scotchbrite pad with a hard backing and a handle for more curvy areas and the propeller See Previous ...
...using one tank of air Tank? Air? Divers? None of the above
...plan to have it hauled, pressure washed, and repainted and zincs replaced soon after his return to the boat...As far as I know the closest Haulout would be over 1000 miles away

Chances are the OP picked up a boat in Thailand or Malaysia and went to Sumatra for the surfing. Now he wants to leave the boat there. There are other problems besides keeping the bottom clean.