Keel weight ideas

[Chris D]

Hey everybody,

       With the inspiration and the spirit of all who have gone before me, with rotten plywood berths and rotten concrete, delaminating fiberglass

etc.,etc., I have taken the liberty of lopping off the deck of my '77 CP16, separating it from the hull. I now have chance to make it nicer inside

and out.  Since the rotten concrete will be coming out of the keel, I have been thinking of how other folks, like Tim of S/V Kpeting ( I have

followed your journey through your blog and now your micro-documentary. Best of luck selling your beautiful boat and congratulations on

Fatherhood) I have considered lead, but it's expensive and it seems sort of hard to come-by in quantities that are needed. So my question is,

what does anyone think of using short sections of train rails embedded in the concrete, to lower the center of gravity? Any advice about that

and other improvements I could do at this time would be appreciated.

Chris

[Pacman]

what does anyone think of using short sections of train rails embedded in the concrete, to lower the center of gravity?

I like the idea.  I have considered excavating a space in the concrete for a deep cycle battery to lower the CG without adding much to overall weight.

More recently I have been thinking of making a steel end plate for the bottom of the keel.  My current design is made from 3/16 steel plate cut to the shape of the keel footprint but with a 3" lip protruding from the sides to increase keel performance.  Added weight would lower the CG a bit but the big benefit should be the end plate effect.

[JTMeissner]

When I chopped out part of the keel, I found steel scrap was already mixed in with the concrete; no idea if part of original pour.

I found that a 50 lb bag of lead shot (recovered from ranges, I suppose) was not cost prohibitive.  I mixed that in with the aggregate when I poured in the fill. Not a whole lot of extra weight but more dense than the concrete alone.

-Justin

[Mas]

Pretty sure that there is metal mixed into the mix when made at Hutchins, actually thought it was lead but never really bothered to track down the facts. I am not sure what inexpensive looks like but lead and gold are next to each other in the periodic table for similar properties but aren't ya glad it is not the same cost!

Here is site that can give ideas and costs, though pretty sure there are less expensive sources.

https://marsmetal.com/counterweights/marine-ballast-weights/

I am no expert on this, but it would make sense that having metal just placed into the keel might allow for shifting and space for any future water intrusion, probably why the concrete/metal combination more than likely used. Lead shot would conform well and conceivably be mixed with something like an epoxy to form a singular shape. I do know of more than one person who left or carved spots for battery(s) to keep the weight lowered and centered. Hey, they have lead!

Meanwhile, isn't it great that the 16's are such a craft that folks want to spend so much time and energy restoring. Speaks volumes about them, but then again we are clearly a bit prejudiced! Good luck Chris with the project and keep us all posted so we may learn and also be excited for you.

Oh.....dont forget pictures!

[Dove16]

Keep us updated! I'm following this with interest as I have the same project ahead of me here and I could use some pics as I prepare for the journey.

[Chris D]

Thanks for your input everyone. I hadn't thought of just sprinkling in lead pieces to the concrete. Maybe that, in combination with the train rail.  Do you think it would be better to seal the train rail with a coating of epoxy to help fend of rust?  Justin, yours was another of the restorations that I followed. Mas, I was thinking of putting the battery in the bow of the boat to help balance the motor and people, but maybe your idea of also creating a space for the battery there could also help with the solution. The rails would be encased in a lesser amount of concrete to prevent shifting and then the whole deal sealed with epoxy.

Also, Justin, did you replace the foam beneath the berths? My understanding is that if the boat fills with water it would sink anyway and, to me, the placement under those berths wouldn't really reduce any noise. I was considering putting access points on the berths and using that space for stowage.

Chris

[JTMeissner]

My technique (described elsewhere in the forum) was to cut out the front and edges of the keel, down a few inches in all areas and to the bottom for about a foot at the front.  Poured in the lead and fast set concrete which filled the hole up front.  Let that set, then covered the entire keel with a high strength grout.  After a few days letting that harden up, the entire keel area was coated with resin, effectively sealing it to water intrusion. The whole area was then painted with truck bedding which was both hard and added some grit that prevents it from being slick when wet.

I took out all the prior foam under the berths.  It was not a complete fill, there were voids.  If you see small circles in your berth wood, that's where they poured in the foam, but it wasn't 100%. Two part foam is not too difficult to work with, but hard to gauge how much for any particular area.  I used about three pours in each berth.  Poured in foam, set board, weighed it down for the set time, lift, find gaps, repeat.  Still not 100%, but more than original.  Or, like the factory, set the berths in place, pour through access holes, cover and go.  IIRC, the foam is really there to keep hull deformation to a minimum if the boat is fork-lifted.

The space under the berths is pretty negligible.  You get a few inches, but it slopes up the outside of the hull pretty quickly.  I also foamed up front when I reset the pad eye. Up there, that may help with deadening any pounding through waves, I think the foam under the berths may be a little too far back to help much there.  I debated foaming the sides of the hatch area in front of the post, but opted to leave it all open.

I'll add photos when I get access to the files, not sure what's still here in the forum and what was lost to Photobucket.

Edit: Added photos.  Forgot I had used the old foam under berths and just filled in the gaps (quite big).  Some links: http://cpyoa.geekworkshosting.com/forum/index.php?topic=9238.msg69974#msg69974

http://cpyoa.geekworkshosting.com/forum/index.php?topic=9242.msg69630#msg69630

Pictures are from Photobucket... Links working again?

-Justin

[Chris D]

Thanks for the pics Justin.
Did you use regular pine for your stringers and bulkhead, or is that pressure treated wood? Is your plywood for the berths marine grade? Treated? I was going to coat it all with epoxy.

I didn't think about the foam for helping to maintain the structural rigidity. I may reconsider the foam situation. When I pulled the berths apart, there was still water under the foam after sitting in the garage for about a 9 months. She did go through a pretty severe series of thunderstorms last summer at Assateague Island, and possibly still had some leaks.
I was wondering if maybe not having foam in there would help it dry faster. I suppose the idea is to not have any water intrusion in the cabin at all.

Chris

[JTMeissner]

The dimensional wood is treated, the bunks were high quality ply (non-marine).  All coated with resin, thickened in the seams, and then a sealing/water resistant primer.

Somewhere along the way in the last move and outdoor storage, I got water in under the berths again.  Not sure how or where... everything seemed sealed tight.  I had to drill weep holes through the stringers and water just poured out into the bilge.  At least I know the water is coming from the top and not from the bottom.  Sitting in the boat marking lines with a dry erase marker to find leaks was not a great rainy day.  I still get splashed rain through the foredeck cowl, so I have to live with some water for now.

-Justin

[philb Junkie19]

Chris,
Don't know how far you have gotten on your keel. I  recently read an account of using polyester resin mixed with sand in a keel to encase metal and fill the space. The sand kept the resin from overheating during cure and filled the space.  I can see why you are looking at rail, lots of weight for the space it takes. I had a little OC3 crawler with a length of rail welded to the top af the blade for extra bite. Worked great.

[Chris D]

Phil,

That is a neat idea. I have been contemplating on whether or not to seal the metal. I wonder how much polyester resin was used and how much sand was used. Does anybody know if the poly resin would bond with the hull well?

I'll have to do a little more research on that. Any links or where you read that?

I just removed all of the concrete and she needs to be cleaned and have a few holes to patch correctly. The hull has seen better times to be sure, but I suppose that all the effort is to make her tip top!

At some point I will try to upload some photos.
Chris

[philb Junkie19]

Chris,
This is what I was thinking about. The writer, a junk rig sailor with many thousands of miles under his keel, is technically proficient and has years of experience in designing and boat building. I pulled this following a member's search on our Junk Rig Association site.

"In Tystie, all of my ballast is internal. It's mainly 25kg lead ingots, with lead shot poured into the gaps, and with cheap polyester resin poured over the lead to keep it in place. I had to buy the ingots by the ton, but the shot came in 25 kg sacks from a place in Hull (I think it was http://www.hullcartridge.co.uk/). In Ivory Gull, I used dry sand to fill the gaps between iron ingots and to absorb the exothermic heat from the resin."