Dirty bottom

[slag]

How much grit does it really take on the bottom of a boat before decreased speed is really noticed? I've seen boats that aren't completely smooth on the bottom to ones that feel like 40 grit sandpaper (to worse!), but wonder, how much growth is acceptable before it really impacts boat performance. The boat will be up on plane so not much will really be in contact with the water.

 

[Beefer]

Re: Dirty bottom

Trouble is, that if there's enough growth, you won't get up on plane.

It's my understanding that any growth will impact the boat's performance. I have to clean my bottom monthly, and I last did it on Sunday. Going to the beach (where I cleaned it), she wouldn't go over 22mph. Coming back after about 75% of the bottom was scraped, I was doing 27mph. Those are gps numbers. I have now contracted with a guy to bottom clean me once a month.

If you're in salt, that gritty stuff you're feeling are most likely the barnacles getting hold. Each one of those bumps will become a barnacle.

 

[slag]

Re: Dirty bottom

Freshwater only, when dry, it feels a bit like sandpaper but not as bad Definitely a few bumps every inch and you can visually see light brown against the white hull. Will pressure washing get this off, or is this a job for Muriatic acid?

This is my neighbor's boat.

 

[Fireman431]

Re: Dirty bottom

There have been tests done to show that a slightly rough bottom will actually go faster than a smooth one. This is based on the results of tiny air bubbles forming in the miniscule recesses of the rough bottom and allowing the water to pass over them.

If you don't have algae, mussels, oysters, or other signigicant palpable residue on the bottom, I'm sure you probably wouldn't notice the difference.

The biggest thing that is going to slow your boat down (other than the large growth) is running against the wind, against the current, load in the boat, and having a vessel out of tune.