Does hard growth actually damage the bottom or is it just a drag problem?

[rick-lamb]

It's been too long since I anti-fouled the bottom of the boat and there's some hard growth on the keel, is this likely to damage anything if I ignore it for 6 months? (not likely to be sailing soon due to new baby)

I'm thinking the worst that could happen is it gets too fouled to move under it's own power and needs a tow to the haul-out...

Anybody ever heard of mussels sinking a boat?

 

[AngusMcDoon]

The white cement-like stuff left by barnacles seems to be harder than gelcoat. Don't see how it could damage the surface, but it's very difficult to remove completely without scraping and scratching. If it's on a metal keel can't see it would do any damage.

 

[William_H]

The hard encrustation will damage a shiny gelcoat. I see this often with people with shiny bottomed trailer mobos who put the boat ona swing mooring for a wee bit perhaps to work on the trailer. The time goes by usually around here in summer 2 weeks is too long and the gel coat gets damaged by the growth. This especially if they scrape the barnacles off. An acid would be a better way to remove the material.
Anyway in OP case it will do no more harm to leave the barnacles and mussels growing until you are ready to use the boat. Any dame will be to the antifouling paint or possibly gel coat but that damage will be covered by more a/f paint.
However don't let a new babay curtail sailing all together. You can take a baby in the boat in a hammock or basinet very successfully provided mother agrees and you can operate single handed. good luck olewill

 

[Pasarell]

As a barnacle reaches maturity its shell will start to grow down around the sides of the white glue it uses to adhere to the surface. The shell is sharp and will penetrate any coatings and also dig into gel coat. On a keel it will definitely damage any priming system you have over the cast iron. Not too much of a problem while afloat but when you lift out and remove the barnacles the iron will immediately start to corrode in the areas where primer is damaged.
I have a great magnified photo of a barnacle grown in a lab and adhering to an abrasion and impact resistant priming system - the type of coating system used in bulk carrier cargo holds. It shows the primers casually pushed aside by the shell leaving exposed steel substrate. Unfortunately I don't know how to post photos here so you have to take my word for it.
In the case of the OP I can well imagine the prop will be so fouled it won't push the boat along but not that fouling would be so great as to sink the boat unless he's in an extraordinarily bad area for fouling

 

[MASH]

Well, clearly fouling couldn't sink a boat but as Pasarell said it can turn a prop into a water-stirrer, and it takes surprisingly little to do that, just a couple of millimetres of barnacles or growth.
Of more immediate concern is that the water intake isnt blocked, mussels and barnacles seem to like the dark shelter just inside the opening and that can be a costly oversight if it ends up with a hard-worked engine trying to overcome a fouled prop.

Plus, get the boat out of the water and it can stink the yard out if it isn't cleaned pretty quickly especially in warm weather.

 

[Appledore]

Talking about propellers, here's (hopefully) a picture of mine some time ago, after 6 months in the river Tamar. This was even after two coats of 'special' antifouling paint. No speed from the engine, just like a dinner plate revolving, and doing nothing!

 

[josephmoore]

Well, clearly fouling couldn't sink a boat

No, but after scrubbing this level of weed, barnacles and other assorted water creatures off the bottom did make my boat sit nearly an inch higher at the waterline which surprised me.

 

[rick-lamb]

As a barnacle reaches maturity its shell will start to grow down around the sides of the white glue it uses to adhere to the surface. The shell is sharp and will penetrate any coatings and also dig into gel coat. On a keel it will definitely damage any priming system you have over the cast iron. Not too much of a problem while afloat but when you lift out and remove the barnacles the iron will immediately start to corrode in the areas where primer is damaged.
I have a great magnified photo of a barnacle grown in a lab and adhering to an abrasion and impact resistant priming system - the type of coating system used in bulk carrier cargo holds. It shows the primers casually pushed aside by the shell leaving exposed steel substrate. Unfortunately I don't know how to post photos here so you have to take my word for it.
In the case of the OP I can well imagine the prop will be so fouled it won't push the boat along but not that fouling would be so great as to sink the boat unless he's in an extraordinarily bad area for fouling

Thanks for that, so I should apply some kind of primer to the keel when I haul and paint?

Not sure what I intend to paint with, part of the reason for dithering over hauling, I need to change from a hard paint (sensible when I was in L.A. and it was cleaned by a diver frequently) to an ablative that works when the boat sits at the dock for long periods but Washington state has banned copper paint from 2018 so if I use micron 66 or the like it will have to be changed after a couple of haul-outs anyway..

 

[AMCD300]

This was the situation after 2 years unloved on a swinging mooring (seriously)...

Huge sigh of relief from me as all it took was a quick jetwash to get me where (tomorrow) I can start to sand down areas for re-priming and new anti-fouling.

Andy

 

[AMCD300]

Thanks for that, so I should apply some kind of primer to the keel when I haul and paint?

Not sure what I intend to paint with, part of the reason for dithering over hauling, I need to change from a hard paint (sensible when I was in L.A. and it was cleaned by a diver frequently) to an ablative that works when the boat sits at the dock for long periods but Washington state has banned copper paint from 2018 so if I use micron 66 or the like it will have to be changed after a couple of haul-outs anyway..

Have a look at the thread I started this week asking the same question. Lots of good advice re anti-fouling, paint for topsides, anti-slip paint etc:

http://www.ybw.com/forums/showthread.php?363210-Recommended-Paint-for-a-Wooden-Yacht

Hope it helps.

Andy