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rusted center board
How much will a rusted center board kill boat speed on an RL24? When I first got the boat last year, it seemed to glide through the water in almost wind. I had inspected the centerboard and at that time, there was maybe some rust stain, but still in good shape. I've had the boat out once this year, and I seemed to have dramatically lost boat speed. I feel like I'm dragging an anchor. The boat tops out at about 5 knots on a beam reach and barely hit 6 knots down wind in 20 knot winds. Last night i was looking through the center board slot to find a place to drop a cord through to connect up a speed censor. I noticed that the center board is now heavily pitted over most of the surface. Is that likely the source of my loss of boat speed?

BTW: Why don't they build center board from stainless steel sheet metal and back fill them with lead? Seems like the cost would not be that much different, and it would be maintenance free.
Daveinet15-Jun-2015    Edit    Delete 
Re: rusted center board
Davinet.
The rusted and pitted keel will make a considerable difference to the speed and pointing ability of your boat. It is most important that both the keel and rudder do have smooth and properly shaped surfaces.
Rob Legg24-Jun-2015    Edit    Delete 
Re: rusted center board
I have the same issue. At least the front of the centre board is pitted.
Can I have some advice on the best solution?
Sand blast and resurface with?
Robert W 28-Jun-2015    Edit    Delete 
Re: rusted center board
The origonal keels were coated with 5 coats of a tar epoxy finish, but, that was banned some years ago,so I would suggest using an epoxy filler followed by an epoxy based paint.
If anyone has recently found a better solution please add it to this discussion
Rob Legg28-Jun-2015    Edit    Delete 
Re: rusted center board
Molasses syrup mixed with water will dissolve rust. It may take a weak, but it will dissolve it without touching the cast iron. Mix 4:1. There are some good Youtube videos regarding this. I would then spray it with cold Galvanizing paint. Permatex makes this. Its about 70% zinc solids. My assumption would be to then coat it with epoxy, and then same it smooth. Epoxy should be much easier to sand smooth than cast iron.
To me, the hard part is going to be removing the centerboard. I think I can move the boat forward about 8 inches, which will allow the board to drop down. I figure if I park the trailer on ramps, that should give me enough space to drop it out below the boat. Not looking forward to it either way.
Daveinet28-Jun-2015    Edit    Delete 
Re: rusted center board
when I had a '24, I removed my 'board to clean and check and also to try and stop the knock.
With help of my mate we suspended the boat from his carport and rolled the trailer out (we did support the 'sus' end with an accro prop)
The boat was about 1mtr from the ground and I lowered the board using the internal winch then supported the bolt end with a car jack.
Much shouting and co-ordinating ensured that the operation went smoothly.
luckily my board needed very little work so I didn't need to "wrestle" it out,(phew)
I did araldite 2 strips of formica each side of the board which stopped the knock and sailed the boat for 5 yrs after with the same result (for further info, contact P Warnes as he now has this wonderful '24)
PS when the board is out, replace the wire retriever with spectra. When my wire broke I replaced it with said material and used a bowline to attach it. 5 years later, I replaced the retriever as per the agreement on sale. The Spectra was still in perfect condition, even around attachment point.
Hope this is some help,
regards
Martyn

martyn29-Jun-2015    Edit    Delete 
Re: rusted center board
When the problem with the cast iron keel surface is pitting it usually points towards a electrolysis action. For this to happen the boat would have to be kept afloat on a sea water mooring for some time. During this period an electrolysis reaction ( pitting) would happen on the cast iron keel, this would be caused by a reaction between the stainless steel keel bolt and the cast iron keel.

Robert W post is a classic example because the the pitting in his keel was on the leading edge of the keel. This is the area that would have been submerged in sea water when the swing keel was stowed in the up position.

The only way to stop the above action is to keep the hull on the trailer and away from sea water. If this is not possible you could install a sacrificial anode into the circuit using say a zinc anode, This anode would accept all the pitting in the system and keep it away from the cast iron keel.
Alastair Russell1-Jul-2015    Edit    Delete 
Re: rusted center board
Not sure about your theory, as my boat is stored on a trailer, and sailed in fresh water. It only once has been in the water for more than a couple hours at a time, during my 1 week of vacation, where it spent 4 days in fresh water. Otherwise it has only been wet at any given time, 3-hours tops.
daveinet2-Jul-2015    Edit    Delete 
Re: rusted center board
Daveinet

Google 'Galvanic Corrosion' and 'Metal Corrosion' and have a looksee. I just cannot believe that all the pitting/corrosion you described has taking place in the one year you have owned the boat.

If you go ahead and make a stainless swing keel ensure that the keel and the keel bolt are made from from the same marine grade stainless steel ( 316 or 316L). You can have Galvanic pitting,corrosion and also transcrystaline cracking using non marine or mixed grade stainless steels.

I found that pulling the RL24 over with the mast up using the spinnaker halyard was easiest way. I drop the boat off the trailer onto soft grass and then use my car to pull the boat over 90 degrees and then I lash the mast to the car before working on or removing the keel.


Alastair Russell3-Jul-2015    Edit    Delete 
Re: rusted center board
Unfortunately, I do not have enough length in my yard to the boat, trailer, and car, all in a straight line. I have the length, but because of tree limbs, there would be no way to put the mast up to roll it over.
We do get some salt in the air from road salt, but the boat is in the back yard during the winter. I was surprised to see it rust that much in that short of time. Being that is is stored on the lawn, makes me wonder if the board stays wet from condensation. I know from week to week, the board doesn't really dry out.

I went out for a sai... - OK, can't really call it sail when the wind never exceeds 2 knots - maybe I should say I went out for a spin tow days ago. When the wind did actually blow, I found it very difficult to sail up wind. The wind would blow, but the boat would not move much. I'm pretty convinced I have to address the rust issue, otherwise this boat will just be a pig.
Daveinet5-Jul-2015    Edit    Delete 
Re: rusted center board
From a safety manual for small aluminium boats

Material Condition

In order to maintain the material condition of the aluminum hull, the operator of the R/V Zenith Safety is urged to keep all bilges clean and dry at all times. Furthermore, special attention must be paid to the introduction of dissimilar metals aboard the vessel. For example, a penny or copper wire clippings dropped in the bilge can corrode a hole through the hull in a relatively short period of time. The fiberglass cockpit enclosure of the vessel requires periodic attention through wash down and occasional cleaning and polishing. The attachment of the fiberglass house to the hull should be periodically examined for signs of corrosion. All fishing apparatus and through-hull fittings must be visually examined at least monthly for signs of wear, corrosion, strain, cracking, or potential failure. Use of plain steel bolts, nuts, pipe fittings, hose clamps, or other appurtenances are strongly discouraged. Instead, type 316 stainless steel should be used where possible. Any issue which may be beyond the scope of in-house knowledge or experience shall be brought to the immediate attention of Robbie's Marine Service for correction as soon as practicable. Robbie can be reached at 609-555-4801.

Alastair11-Jul-2015    Edit    Delete 
Re: rusted center board
Well, I sure hope its worth it. I spent all day yesterday sandblasting the centerboard. The sandblaster was a cheapo one, so I was fighting it a good part of the time. At one point, I thought I should just give up and use a wire wheel - wrong. The wire wheel took for ever to cut through the rust. Even with the marginal sand flow at times, the sand blaster was so much faster. There is still just a very minor amount of rust in some of the pitted area. I painted the whole board with molasses syrup. Then covered with cellophane, so it wouldn't dry out. I'll leave that on till next weekend and then pressure wash it. That should take off what ever minor rust was still there.

I ended up needing to dig about a 1 foot deep hole under the board to let it hang down straight.
Daveinet12-Jul-2015    Edit    Delete 

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