Just curious...

[Bernadette & David Hedger]

What are people's opinions and/or experiences with filling those 'hard to get at' bilge spaces between keel and planking, with cement?

[dasboat]

Not a lot of experience,so the grain of salt is advised.
took apart a couple of heavy trawlers to replace keelson and garbor.Did not like the way this wood looked under cement ballast.Punky,little adhesion to the wood so moisture trapped there nicely,and a bear to get out of the way.
Both were DeFever heavy built power boats with a slug of cement from about station 6 to 24(guessing).Ended up banging that stuff out.Whew,tireing to just remember that.
Darryl

[Mike Field]

There was a thread running on pitch a few days ago that seems to indicate it might be a better way to go. (Search and you shall find.)

[ken mcclure]

Ask Ian McColgin. I think I remember him expounding on the topic in an earlier thread.

[Ian McColgin]

Cement in new construction to make a nice run for the water is reputed to lengthen the life of garboards and the hoodends of the frames.

In old construction, it's a pain.

Some use it partly as trimming ballast, pouring after the boat's been launched and swelled a bit.

The ferrocement crowd and probably some local foundation guys can advise you on how much acid to add to make the cement work better and be less an electrolyte.

G'luck

[dasboat]

Ian,will you say more about the acidity of the cement,and the old vs.new construction?
I don't intend to hyjack this thread,so if it isn't important to B & D's question,no answer will be understood.
Darryl

[Carl Stone]

I have a 45' wooden ketch with concrete ballast. since the boat is in salt water, there is no damage from the water trapped between layers after 30 years, but beware that you will not find the source of any leaks unless you haul the boat, and I have never found a way to stop the leaks at the edge of the concrete joint. It will not act as a plug to stop those hard to get at areas, only bring the water up to a level where you can see it. If I could remove mine, I would, it's not harmful, but you never know where a leak is.

[dasboat]

Should have said both boats I dealt with were coastal cruisers,but had slips in fresh water where they spent 80% of their time.
Darryl

[RGM]

Cement is frequently seen in commercial boats for filling voids, doing some leveling and/or adding ballast. It's relatively cheap if you require alot of it. Cement has questionable adhesion (especially long term) and is difficult to remove for hull inspection or repair. Marine pitch can accomplish the filling of pockets and voids that you require with out all of the potential drawbacks of cement. It's not quite as nasty to remove if need be either. Good luck.

[Ian McColgin]

I don't know much about the acid issue except that in ferrocement construction it can be used to prevent electrolytic deterioration of the rod and mesh and it was thought by some that might be helpful on wooden boats whether iron or bronze fastened. But I don't klnow anyone who really knows.

[paladin]

The deterioration of the rod and mesh is a result of microscopic bubbles forming as a chemical reaction to the concrete mixture and the coatings or galvanizing on the metals. It is reccommended to allow the metals to sit outside for a couple of weeks to allow nature to take care of the millscale, galvanizine, oil etc used in the forming of the metal reinforcing material. When fresh mortar is applied to metal reinforcing material it forms a complete galvanic circuit between the zinc coated metal and tie rods of mild steel. You can actually measure this with a volt-ohm-meter.
Achemical, Chromium Trioxide may be added to the water to correct this "problem'. mORE ON THE SUBJECT IF ANYONE IS INTERESTED.......

[dasboat]

Well I'm interested!I'll probably never use the info,but being a curious sort I like to learn of things relevant to this maddness of mine.
Darryl

[Smacksman]

Smacks were ceiled with concrete from new - made shovelling fish out of the hold easier. Mind you, the boats were only built to last about 20-30 years. Alberta's planks are now 116 years old and they looked a bit scruffy where some of the concrete had been chipped out but still a lot of the 1.5" thick pitch pine or larch left - surface damage really. I do go along with the pain of finding leaks mentioned above - I just let her leak a bit.
When the ADC had her concrete out it was full of iron bits and bobs. One bit was a sheave pin about 3/4" dia. that was badly worn on two sides - obviously rotated in the block at some stage to get more wear out of it. Other re-built smacks have tarred the inside then poured lead between the frames. God help the man who has to get that out in the future.
Pity about ferro is that it is difficult to get them insured. They last a long time though and easy to repair.

[WRB]

Sam Crocker specified wax poured to the bottom of the limbers in his designs.... runs like water to fill all cracks and grain and would be very easy to remove.

[WRB]

Sam Crocker specified wax poured to the bottom of the limbers in his designs.... runs like water to fill all cracks and grain and would be very easy to remove.