Engine Bilge, Ballast and Rust

[Christianonthecut]

Hi all, bit of a mixed batch of questions this one.

 

I'm re-wiring for solar and as always seems to be the case, you start one job but end up taking on a whole load of others in the process.

 

My re-wire has led to a decided repaint of the battery area(cruiser stern) which of course means a sort out of the engine/build as well.

 

1st question...

 

It seems that the stern end of my boat has been ballasted with 14 bags of B&Q builders sand. I have of course removed all of this to clean and prep for paint and am concerned by the rust being formed on metal work from the trapped moisture between the polythene bags. Now when I purchased the boat, the previous owner told me that he took it in for blacking 6 months prior to a boatyard who informed him that the stern end needed these 14 bags of builders sand as there wasn't enough ballast at that end. I have always thought that it sits very low in the water at the rear and when opening the taps as it were it can 'dig in' to the point that the exhaust which is way above the water line when stationary actually goes under water.

 

Having removed all of the bags of sand for repaint and sort out the boat now IMO sits more or less evenly in the water and the height has been raised about 2 inches. It's a 1983 hull which I believe to have had a stretch probably about 1996 when it had a full internal refit, so has been on the water without these bags of sand for many years prior to it's blacking experience 18 months ago or so.

 

My question is, how can I tell if the boat needs the ballast or not? Is there a way of measuring how low it should be sitting in the water.

 

2nd question...

 

Rust removal and paint...

 

I have degreased and jet washed the bilge areas and am ready to tackle the rust. There is a little surface bubbling but nothing major, mainly where the bags of sand have been. I was planning to wire wheel the worst of the rust and flaky paint, key the rest, then panel wipe and apply Bonda Rust Primer straight to the rust and then Danboline as top coat.

Would it be advisable to use a rust netraliser on the steel before applying the bonda or will the bonda apply straight to the wire brushed and cleaned up metal?

 

Sorry for the long questions and I appreciate peoples time and advice in advance. Thank you.

[ditchcrawler]

Is the propeller in the water for a start, can you see daylight under the "utoxitor" plate? (cant spell that, the back end)

[Christianonthecut]

Yes, propeller in water and no, can't see daylight. Seems to be about an inch of water inside weed hatch to the bottom plate with the sand bags now removed.

[ditchcrawler]

Yes, propeller in water and no, can't see daylight. Seems to be about an inch of water inside weed hatch to the bottom plate with the sand bags now removed.

Sounds OK to me, what is the other end doing now, has that gone down as the back came up

?

[Christianonthecut]

It's gone down very slightly but seems to sit better in the water now. Water tank is full and Diesel tank is about 1/8 full at present.

 

Do you think I could safely lose the sand?

Edited May 18, 2013 by Christianonthecut

[PhilR]

It's gone down very slightly but seems to sit better in the water now. Water tank is full and Diesel tank is about 1/8 full at present.

 

Do you think I could safely lose the sand?

 

Definately get rid of the sand. If the uxter plate is 1 inch below water, with an almost empty fuel tank, you don't want to be adding ballast at the stern - unless you are suffering from propellor cavitation, which is unlikely.

 

Others might disagree, but I reckon an uxter plate should be between ½ and 1½ inches below water when the boat is stationery. Underway it will probably sit somewhat lower in the water.

 

If you can keep the bilge area permanently dry I wouldn't worry too much about paint and rust treatment. Remove loose rust and dirt and give a dosing of Owatrol oil. Then settle back and enjoy a few beers..............

 

Good luck

[Christianonthecut]

Excellent, I can build a beach at the side of my mooring now!!

 

Not familair with Owatrol oil, will take a look, thanks Phil.