How slow does weed make a yacht go?

[AntarcticPilot]

Weed or Barney Kulls will easily make that sort of difference. Move back to your river location now & again during the season. Stuff that lives in sea water often can't cope with fresh & vice versa.

I am moored in a river/creek, mostly fresh water at low tide & salt at HW. Very little growth of weed or Barney Kulls - to the point where I only have one coat of A/F every other year.

Ditto in a marina with a strong fresh-water inflow. Surface water is pretty much fresh. Down-side is that fresh-water freezes more readily than salt, so the marina freezes during a cold spell in winter!

 

[trapezeartist]

A question for the forumites who frequently dive to scrub their bottoms:
How many times can you scrub before you lose all the anti-foul?

I am rather disappointed to find the first signs of weed appearing about three months after anti-fouling. Am I expecting too much?

I occasionally monitor drag by motoring at full throttle. Brand new anti-foul gave 6.9 knots. After a month or two, down to 6.8 knots. Last time I checked, 6.6 knots, but it climbed up to 6.7 knots after 15 minutes or so. These speeds are suck-it-and-see estimates of the average speed arrived at by watching the log constantly over a period of a minute or two.

 

[Scotty_Tradewind]

Can a growth of weed make that amount of difference?

Yes it could make even more.
MyTwister loses a knot from its best speed in a F4-5.
This would be after two and a half months on its swinging mooring, being sailed most weekends.
For example I had her jetwashed at Cowes last year 3rd week of June and did b4 and after tests on the engine both ways at low tide.
5.4knots before jet washing with engine flat out, 6.5 after.
A boat with a larger wetted surface area would presumably be liable to lose more??

 

[William_H]

Antifoul paint

A question for the forumites who frequently dive to scrub their bottoms:
How many times can you scrub before you lose all the anti-foul?

I am rather disappointed to find the first signs of weed appearing about three months after anti-fouling. Am I expecting too much?

There are antifoul paints that are self ablating so quite soft and then others are harder described as hard racing a/f. So some will take cleaning better than others.
I can't comment about 3 months after painting. I get the same effect after 1 month but that is in summer with warm water. I noticed last weekend that my hull is surprisingly clean for the last month it has been in with very little a/f left on, butit is mid winter here and boat is usually tucked up at home.
I normally relaunch in Spring repaint in early summer and hope it lasts through the season with in the end a lot of scrubbing until by end of season about 50% of all a/f has gone. I do make a point of only puting on a single coat so that by next paint time there is not much sanding down to be done. it suits me anyway.
Ultimately you will have to figure out a regime that suits you but certainly start by wiping with a soft sponge. You want minimum paint removal to get it clean. I end up with scotch brite scouring pads then near pull out time I use wet and dry sand paper. But this is part of the preparation for next repaint. My boat sits on a trailer so in some places it is easier to sand down in the water than out. olewill

 

[Seven Spades]

My boat goes back in the water in March, by July it is ready for a lift an jet off. Is this normal?

 

[cliffordpope]

Missis and I are both divers. I spent two weekends layiing our mooring at Dale, so am I right in thinking it's her turn with the scraper......?

Have you ever tried scraping a boat while swimming in the water? It's impossible because there is nothing to push against.

 

[Alcyone]

Have you ever tried scraping a boat while swimming in the water? It's impossible because there is nothing to push against.

Yes. Not impossible, but very difficult, and tiring. It'll keep her fit, though.

 

[William_H]

Have you ever tried scraping a boat while swimming in the water? It's impossible because there is nothing to push against.

No not impossible just difficult.
For some years when my boys needed pocket money they did boat cleaning. They had a few clients getting cleaned each fortnight. at 5 squid for small a bit more for bigger. And yes being teen agers I ended up doing some of them cos they were busy. It was a good pocket money job as they could do it any time to suit them. (proffessionals here now do a smal boat for 25 squid)
A smaller boat is much easier in that you can hang onto the gunwhale with one hand this gives you a decent reach under and your weight hanging on your arm gives a good stabilising effect. Obviously you have to dive under for the under hull and keel. It is easy provided that barnacles have not got a grip.
For really bad growth (coral reef) I found a really heavy scraper is called for. I use a bricklayer's bolster (brick cutting chisel) the inertia of the chisel will smash the shells. Even then it is not really practical to do a whole boat unless you do it in multiple days of short intensive effort. Any strong tide flow will make it difficult and on bigger boats a rope tied around the hull may give some support. olewill

 

[longjohnsilver]

I think therein lies the problem. In Cardiff bay, it's fresh water, with periods out in the channel. Last year, it was a river mooring, with periods in the sea. This year, it's all salt water.

Thanks for all of your replies. Missis and I are both divers. I spent two weekends layiing our mooring at Dale, so am I right in thinking it's her turn with the scraper......?

You'll probably find that most of the growth comes off with a wipe with a scotchbrite pad. I also use stainless wire wool on the props and shafts (these are the most important bits to keep clean). I can do my 48 footer in about an hour, quite hard work but well worth it. Choose somewhere with good vis and a bit of tide to move the muck away. Also suggest using a wet suit rather than a dry bag as you/she will get pretty warm. And wear gloves, lots of potentially sharp bits down there!

 

[lw395]

You'll probably find that most of the growth comes off with a wipe with a scotchbrite pad. I also use stainless wire wool on the props and shafts (these are the most important bits to keep clean). I can do my 48 footer in about an hour, quite hard work but well worth it. Choose somewhere with good vis and a bit of tide to move the muck away. Also suggest using a wet suit rather than a dry bag as you/she will get pretty warm. And wear gloves, lots of potentially sharp bits down there!

I find a good tool is a flexible plastic ruler, you bend it around the hull and scrape a wide swath in one go. Just don't use it for nav afterwards, as it soon wears into a curve. It does not clog like brushes or scotchbrite.
I prefer a drybag, all the muck you dislodge seems to try to get inside your wetsuit!

A bit of tide helps, as you say. Too much becomes very hard work!
Gloves- kevlar builders gloves, you can rub the hull with them to good effect without fear of cuts. Screwfix.