Will it Sink?

This is the place to post your ideas, thoughts, questions and comments as relates to general boatbuilding and reconstruction techniques and procedures (i.e. recoring, epoxy, fiberglass, wood, etc.)
Post Reply
Hesper(II)
Bottom Sanding Grunt
Posts: 9
Joined: Mon Dec 06, 2010 6:12 pm
Boat Name: to be named
Boat Type: Morgan 24

Will it Sink?

Post by Hesper(II) »

In a related question to my previous question about my centerboard, what say you experts about a wooden centerboard? It seems my board for my Morgan 24 is a replacement. It apprears to be made of plywood(likely marine grade as it did get wet but i can see no deterioration). It is about 4.5 feet long, maybe 18 inches wide, and after grinding, about 3 inches thick at thickest. Question is, before I go through refiberglassing, painting etc, Will it Sink?

This is a swing keel affair so once it's in and in the water, i will not have a chance to change and there is no easy way to push down the board if it doesn't go down on its own.

I could bore out a hole and pour in lead shot or something before reglassing but would prefer to not do much more work and go sailing. If need weight, any idea how much?

Thanks
User avatar
cantstopnow
Master Varnisher
Posts: 106
Joined: Tue Nov 14, 2006 8:05 pm
Boat Name: Ariadne
Boat Type: Morgan M34
Location: Chebeague Island, ME
Contact:

Re: Will it Sink?

Post by cantstopnow »

At the risk of seeming obvious, put it in some water and test it?
Today is a great day to Go Sailing
1966 Morgan M34 K/CB
1965 Pearson Commander
1977 kells 28
1973 Paceship PY23
1971 Compac CP 16
Quetzalsailor
Master of the Arcane
Posts: 1100
Joined: Fri Aug 26, 2005 9:53 am
Boat Name: Quetzal
Boat Type: LeComte North East 38
Location: Philadelphia, PA

Re: Will it Sink?

Post by Quetzalsailor »

If you don't/can't pull it down, it has to sink on its own. As for testing how much weight, only the lower end has to sink, so weight at the lower end of the right amount is all that's required. Testing, therefore, would involve holding the board on edge and pivoted on its pin at the right depth in the water; then add weight to the bottom end until it not only sinks, but sinks with enough force to overcome the drag in the slot when head to wind.

Flying Dutchman dinghies have tackles to pull the board down or up, as well as fore and aft (!!! - the pivot is on a tracked bracket). You can adjust the board even when close hauled, against the friction generated by the lateral force of its doing its job.

You know, I hope, that there is (was?) a very fine Morgan website and forum and these questions were common. Particularly common about replacing the pennant.
Hesper(II)
Bottom Sanding Grunt
Posts: 9
Joined: Mon Dec 06, 2010 6:12 pm
Boat Name: to be named
Boat Type: Morgan 24

Re: Will it Sink?

Post by Hesper(II) »

Thanks!

Yeah, the water test was on my mind but I was hoping someone knew if marine plywood was bouyant, neutral, or sinks before i went through reglassing the board. Obviously wouldn't want to submerge a wooden board then have to wait till it dried out to glass it. In any event, I did some glassing this morning and might do a sink test before painting. I'm not real concerned as I can give the board a little nudge to get it down if it's neutral. Next year, a new steel/composite board perhaps.
Here's the link to the Morgan 24 website by Bob Horan if anyone's interested. Bob is great at answering emails too. http://morgan24site.com.istemp.com/
TampaBay
Candidate for Boat-Obsession Medal
Posts: 391
Joined: Wed Sep 30, 2009 3:46 pm
Boat Type: Coronado 15

Re: Will it Sink?

Post by TampaBay »

To test my centerboard, I lowered it into the swimming pool. It floated just about where its water line is, when in the down position.
Hesper(II)
Bottom Sanding Grunt
Posts: 9
Joined: Mon Dec 06, 2010 6:12 pm
Boat Name: to be named
Boat Type: Morgan 24

Re: Will it Sink?

Post by Hesper(II) »

So, got the board in after some experimentation with the length of the pennant etc. Goes up and down smoothly. Sadly, we are apparently at neutral bouyancy at best. I know, I should have tested, should have just gone ahead and put some lead in it but damn it, I wanted to go in the water!

Anyway, I do have young sons who will jump in when we head out to push the board down and once it's down, it seems to stay there. No hope of a fix while in the water but that's OK, she still sails fine without board down.

Next question is, has anyone done a blog, thread, etc on building a centerboard out of steel and fiberglass? That is what I see as the original and probably the best and cheapest replacement. It's a long winter so will be looking at doing it after hauled if the fall.

Thanks.
Zach
Boat Obsession Medal Finalist
Posts: 684
Joined: Wed Jan 25, 2006 6:28 pm
Location: Beaufort, North Carolina
Contact:

Re: Will it Sink?

Post by Zach »

If you are concerned about it, the easiest way to get it to sink on its own or stay down is to fill a cavity full of lead.

It used to be a common thing done on the old wooden boats with big wooden rudders. The boat would heel over, the rudder would float and give more weather helm than it ought... They would carve a star or circle, where the wood got narrower in the middle than on each side and pour molten lead in so it stayed trapped and would fall out due to geometry.

I have had a lot of success using lead shot and epoxy together to make things heavier, just route out a slot big enough to put 5-10 lbs in at the bottom of the blade, so it has the length to be leverage. I'd just fire up the router and go half way through the blade through a 6x6inch area. Fill up the cavity with lead shot. Grind back the glass 2-3 inches around the area, underfill the lead shot in the hole and start filling it with un-thickened epoxy. Once the epoxy gels, pull a layer of cabosil across it and apply a layer of 1708 to the patch. Let it kick, sand the next day and splash it...

I wish more people would do this on kick up rudders. I'm working on a big catamaran that could use some lead in the rudders...

Zach
1961 Pearson Triton
http://pylasteki.blogspot.com/
1942 Coast Guard Cutter - Rebuild
http://83footernoel.blogspot.com/
Post Reply