Thanks Jerry - you definitely did some half-round stiffeners, 'cause I have that on #38 M17. They could be foam half rounds, I haven't busted one open to see if there's anything inside :-) Would make sense as you were using foam slab for cockpit floor and locker hatch stiffening in that boat. Can't look right now but I think some of them I know are not foam half-rounds 'cause I can see an open end. At least one somewhere I could see what looked like a half-tube of cardboard providing the form for the glass and resin. Also on my boat half-rounds are used to stiffen the V-berth platform. cheers, John On 9/17/21 9:45 AM, jerry montgomery wrote:
In the very early days we experimented with several ways to stiffen things, before balsa became easily available. I never used the typical (at that time) plywood core because I hate weight in the deck; it's anti-ballast.
I honestly don't remember half-tubes altho they are very good stiffeners, but we made a few with foam half round ribs.
When I started building the 17, in '73, some of the custom builders were using balsa and I watched those guys very closely. When C&C, in Canada, started using balsa I quickly followed. A salesman walked into my shop and told me that he wanted me to look at a revolutionary new material and flopped down a panel of balsa. He was blown away that I knew what it was. I said how much? Send me some. Great stuff; only vice is dry rot. Makes for lighter and stronger decks. Decks on the Sages are carbon and balsa which is most of the reason they are so stiff and fast. Better living thru chemistry.
------------------------------------------------------------------------ *From:* John Schinnerer via montgomery_boats <montgomery_boats@mailman.xmission.com> *Sent:* Thursday, September 16, 2021 7:20 PM *To:* montgomery_boats@mailman.xmission.com <montgomery_boats@mailman.xmission.com> *Cc:* John Schinnerer <john@eco-living.net> *Subject:* M_Boats: Re: Maintenance questions - deck core (or not) Addendum - there is a small area of some kind of core material in my cabin top, between the half-tube stiffeners where the mast step/compression post is. I don't know if it's balsa or foam. I'd guess foam since the only other core material on my M17 is foam. I pulled those machine screws & nuts to put bedding at the holes under the tabernacle (there was no sign of any having ever been there) a couple years ago. Everything seemed solid and clean, no sign of rotting balsa.
cheers, John
On 9/16/21 7:13 PM, John Schinnerer via montgomery_boats wrote:
For an M17, depends on your year. Or maybe varies from boat to boat in the early days?
Mine is M17 #38, 1974, and there is no balsa core anywhere in the topsides mold layup that I am aware of or have so far discovered. And I've explored most all of it for one reason or another. Re-bedded most everything and added some jib furling guides & clamcleat, port side bow cleat, main halyard to cockpit cheek block & cam cleat. Had the window frames out at one point also.
My cabin side decks, sides, & top are stiffened with glassed half-tubes underneath, running side to side, fore and aft of the shroud chainplates and mast step. Also several of same reinforcing the fore-deck between front of cabin and bow stem. Brilliant if you ask me - all glass, nothing to rot if a penetration lets water in, one layer, no core to cut and place, no chance of delamination/poor bond, etc. I am really glad I have this layup.
Just means there's a few narrow strips of locations fore to aft where you wouldn't want to install any hardware above, because the bolt(s) would come thru where a stiffening half-tube is.
Cockpit floor and locker hatch cores are foam, not balsa, on mine.
Maybe it was that way until change of topsides mold, from flush hatch to raised? Don't know when that was. Just guessing. Jerry we may need the story from you on this...
cheers, John
On 9/16/21 6:39 PM, Dave Scobie wrote:
Andrei.
Almost all horizontal sections of the deck are balsa cored. Same for M15 and the Sage 15/SC/17. See my prior email that has links to my BLOG and details rebedding deck hardware.
As you are keeping the boat in-water did extended periods what antifouling are you using on the hull and centerboard?
:: Dave Scobie :: M6'8" #650 :: SV SWALLOW - sv-swallow.com :: former owner M17 #375 SWEET PEA - m17-375.com :: former owner M15 #288 SCRED - m15namedscred.wordpress.com <<-- new site!
On Thu, Sep 16, 2021, 6:32 PM Andrei via montgomery_boats < montgomery_boats@mailman.xmission.com> wrote:
Jerry, do you know if the cabin top where the hand rail attaches is solid glass or it is balsa core? If it were solid glass it would take some of the pressure off of doing this repair right away.
Andrei.
-- John Schinnerer - M.A., Whole Systems Design -------------------------------------------- - Eco-Living - Whole Systems Design Services People - Place - Learning - Integration john@eco-living.net - 510.982.1334 http://eco-living.net <http://eco-living.net> http://sociocracyconsulting.com <http://sociocracyconsulting.com>
-- John Schinnerer - M.A., Whole Systems Design -------------------------------------------- - Eco-Living - Whole Systems Design Services People - Place - Learning - Integration john@eco-living.net - 510.982.1334 http://eco-living.net http://sociocracyconsulting.com