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Go Back   SailNet Community > On Board > Gear & Maintenance > Build a Swing Keel from Scratch - ''74 Helsen 20'' Sloop
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Thread: Build a Swing Keel from Scratch - ''74 Helsen 20'' Sloop Reply to Thread
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Topic Review (Newest First)
06-10-2012 03:49 PM
brehm62
Re: Build a Swing Keel from Scratch - ''74 Helsen 20'' Sloop

This picture is four days later so I would have sanded and put on some more glass on the second day and this would be two days later after some more sanding. I typically waited two days after a layup to sand.

I wanted to test my boat rather than wait until everything was perfect. I had to cut about 3/4" off the length of the aluminum so it would fit within the length of the slot. I wasn't sure of the exact length until I had it in the slot and obviously I couldn't drill the hole until I knew the length. I drilled a hole and sanded the corners off so that the end was round. I found that the piece was a bit thicker than the swagged fitting on the end of the cable so I did sand some more to make it thinner. The last picture is with the cable attached.
05-10-2012 11:10 AM
brehm62
Re: Build a Swing Keel from Scratch - ''74 Helsen 20'' Sloop

Here you can see that I've sanded off more of the polyester resin. I've also cut a piece from the aluminum stock. I used the original strap as a guide for the holes. However I did still have to adjust the holes a bit to get them to line up. You can also see where I did put some small notches and grooves in the aluminum to give it a little more grip on the fiberglass.

Basically, I mixed up a batch of epoxy thickened with fumed silica (petrified snow). I put down a layer over the lead both to glue the aluminum to it and to fill in the slight unevenness of the surface. Then I put the screws into the holes in the aluminum and hand tightened them with a screwdriver. I just wanted them snug.

Then I did a sequence of batches of epoxy and layups over the aluminum. I think the next picture is after three 3 ounces batches of epoxy with a number of layers of glass fabric.
04-26-2012 12:01 PM
brehm62
Re: Build a Swing Keel from Scratch - ''''74 Helsen 20'''' Sloop

Quote:
Originally Posted by Chris12345 View Post
Have you considered making a new keel out of solid aluminium plate?
The original posting is from 2002.

I began posting in this thread because I have a Helsen design boat and I am currently working on the centerboard. I thought it might be useful if someone else needed to do some centerboard repair.

Solid aluminum plate would not be heavy enough. At only 58% of the necessary density my 80 lb keel, for example, would only weigh 46 lbs.

Quote:
If you want it ultra cheap, I would try ferro-cement first
I estimate my keel to be nearly twice as heavy as concrete. I assume that the ferro part would be rebar. To get enough density you would need about 42% of the volume to be rebar.

Quote:
painted with epoxy I think it could last forever
The problem is that if you get a crack that lets water in the steel will rust. The rusting steel expands and makes the crack worse.

My centerboard retracts into a slot so it isn't easy to inspect either when in the water or when on the trailer.
04-26-2012 12:18 AM
brehm62
Re: Build a Swing Keel from Scratch - ''74 Helsen 20'' Sloop

I estimate the original hard attachment as 1/16" x 5/8" stainless steel. I did buy a stainless steel eye-bolt but I changed my mind since it would tend to concentrate the forces when pulled to the side.

Since none of the hardware stores carry stainless stock, I decided to use aluminum which is readily available. I bought this piece at my local hardware store. It is 1/4" x 1" aluminum. It appears stiff enough to me to avoid cracking the end as the old piece did. Obviously I'll use more glass fabric to attach it rather than just lots of polyester resin like the old design. I bought new pan head stainless screws to attach it to the lead plate. The original used two flat head and one pan head. However, since the stainless strap wasn't deep enough for countersinking the flat head screws didn't serve any purpose in stabilizing the piece. I mostly want to replace the screws just to make sure that any end force is not relying entirely on adhesion from the epoxy. I could possibly groove the aluminum for extra grip.
04-10-2012 09:21 PM
brehm62
Re: Build a Swing Keel from Scratch - ''74 Helsen 20'' Sloop

I used a belt sander with coarse grit to remove part of the end of the centerboard. You might wonder how I knew which side to sand since the lead weight is not centered. Basically, I sanded on the side where it was cracked.

You can see that the original embedded stainless strap was too thin. It bent like a pretzel under load from the winch.

The dark gray is regular fiberglass. The light gray is nothing but polyester resin.

They used stainless steel screws to attach the strap to the lead weighting before it was covered.

You can tell that it is lead because I can easily scratch it with my fingernail.

This hard attachment point will have to be replaced with something sturdier. What you can't see here is how the end of the centerboard cracked due to stresses from the strap. This apparently happened both because the flexible strap allowed forces to concentrate at the tip and because the fiberglass was not thick enough. For example, I don't believe that any polyester filler should have been used within the span of the strap.
03-31-2012 10:29 PM
brehm62
Re: Build a Swing Keel from Scratch - ''74 Helsen 20'' Sloop

Quote:
Originally Posted by branon View Post
The original swing keel is said to have been a fiberglass shell with lead ingots. The previous owners apparently rebuilt the swing keel out of steel slats, lots of resin, some kind of lightweight cement material and fiberglass fabric.

In any event, I now need to build a new one. According to other owners I''ve located, the original swing keel was only 100 pounds, but it is 56 inches long, approximately 10 inches deep, and 1.5 inches wide and looks like a simple daggerboard.
I know that this is an old thread but this description seems to match my keel which I'm quite certain is stock. My boat appears to be a 1980 Helsen derivative.

My keel weighs 80 lbs. This is not from a manual; I weighed it.
You can see that it is 56 inches long.
It is 10" wide.
It is 1 3/8" (1.375") thick.
It is a simple center board with rounded nose and tapered trailing edge.

I estimate the density at about 90% heavier than concrete or about 60% of solid iron. I will probably have to repair the cable attachment point because it is a simple embedded flat metal strap that has been bent several times. I would probably replace this with a stainless steel eye-bolt. Obviously if I strip the end to fix the strap I'll find out what the interior is underneath the fiberglass. I agree that it must have lead of some kind to increase the weight.

I've wondered how strong the stock keel might be. Finding out what the interior is made of might show how strong is. This could possibly help if someone else with a Helsen design needs a keel repair or replacement.
07-10-2009 03:18 PM
Irelandbound
Helsen 20

I have completed restore just missing paint !I also have a spare mast in St.Pete Florida
Have a great day
05-16-2009 12:23 PM
Aqualung76
Swing Keel

Hello I am new to this forum and new to sailing as well. I have Macgregor 25 which I just launched for the first time. Believe it or not as I was lowering the keel the winch lock gave out and the keel free fell. There must have been a crack by the pivot bolt because the keel is now at the bottom of the River. I am having trouble finding a replacement keel. Is it possible to use a different keel that would fit on my boat. Thanks in advance.
05-11-2009 09:41 PM
souljour2000 I dunno much about Helsen 20's but I own a 1983 Hunter 20 since July of '08 and have had to re-bed the plate that holds the pin for the keel and replace the bolts. I managed to do this with the boat on the trailer though I don't recommend doing it that way. The Hunter 20 is a nice little boat that weighs about 1700 lbs with 400 of that in the iron swing keel...A good boat for 2-3 people to camp on but really ideal for one to camp in comfort. My 5hp tohatsu pushes it along real well and I just took it a mile and a half out into the Gulf of Mexico yesterday...with a good eye on the weather I am going to go 3 miles next time to a reef. That will be my limit most likely.
05-08-2009 08:59 AM
Streaker20 Thanks for photos . I am planning on removing the centerboard and refinish it, and can post some profile measurements if you need to totally rebuild it.
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