Dave – I’m just checking something. I replied to your message of 4/2/21. It shows that it sent, but I don’t see it on the site. Maybe I can’t see my reply? Can you verify that you received a message from me on 4/2/21? Thanks. Sent from Mail for Windows 10 From: Dave Scobie Sent: Wednesday, March 31, 2021 3:43 PM To: For and about Montgomery Sailboats Subject: M_Boats: Re: Transom mounted ladder on M17 Gary: What John writes is very detailed and covers all the bases. To add - * yes above the seats is cored and I believe plywood core. you can see that the chainplates bolt straight through this section of the transom (on the older '1st gen outboard motor cutout M17s) and are backed with some washers. I'd use large fender washers for a boarding ladder. * yes, as John wrote, you need a backing plate (in addition to fender washers) for the lower mounts. sharing a picture, or a www-link, of what you want to install would be great as folks can comment if using the same, etc. :: Dave Scobie :: SV SWALLOW - https://sv-swallow.com :: Montgomery 6'8" #650 :: Truck camper - https://truckpopupcamper.wordpress.com/ :: Ramblings - https://scoobsramblings.wordpress.com/ :: former M17 owner #375 SWEET PEA - https://m17-375.com/ <http://www.m17-375.webs.com/> :: former M15 owner #288 - http://www.freewebs.com/m15-name-scred On Wed, Mar 31, 2021 at 12:45 PM John Schinnerer via montgomery_boats < montgomery_boats@mailman.xmission.com> wrote:
Can you send a link to the ladder make/model you are installing?
Then we can see how it attaches, how the leverage on it will work and where the stress will be.
If it's like most, when someone puts weight on the rungs there will be a pull on the upper attachment points and a push on the lower ones.
In general, if you think the motor mount side needs reinforcing (it does), the ladder side all the more so needs reinforcing.
On the motor side you've got 30-60+ lbs static weight (depending on what motor you have), and then whatever dynamic force comes from cranking up the throttle rapidly, pushing hard on the bottom of the lever that is the motor shaft, which pushes in on bottom of mount and pulls out on top of mount.
On the ladder side, you've got a static weight of whatever you or your heaviest friend who swims from the boat weights - so 200+ lbs potentially. And, whatever dynamic force comes from them hauling whatever their weight is up (and down) the ladder - which is a push in on the bottom (feet) and a pull out on the top (arms) - like the motor, but potentially more force. The longer the step extension below the mount point, the more force.
So absolutely I would reinforce it, as much or more as the motor mount side.
On my 1974 M17 the transom below the cockpit seat is just hull fiberglass, however many layers were in the layup, but there was no other reinforcing.
I remounted the ladder that came with the boat (just a two-step with bottom one flipping up when stowed), putting an epoxy-coated plywood backing plate that is much larger than just covering the bolt points and is epoxied to the transom.
Before, when I at ~150 lbs. went up or down the ladder I could see the transom flex. More so my heavier friends.
Now, basically no flex at all, solid as a rock. I had previously done same for my motor mount, which all but eliminated transom flexing on that side as well.
cheers, John
On 3/31/21 11:47 AM, Gary Froeschner wrote:
I am installing a permanent, transom mounted, fold down, 4 step, SS ladder on my 1976 M-17. It mounts with 2 clips at the top & 2 round stand-offs at the bottom. The clips have 2 bolts each. The stand offs use 3 bolts each. All the fasteners are ¼”-20 bolts, lock nuts, & fender washers.
I’m curious if the group feels that the transom needs to be reinforced for these attachments.
My transom above the cockpit seat is 1.125” thick fiberglass and plywood (I think) core. This seems to me adequate for the clip attachments. I think the transom gets a little thinner below the seat, but I think it still should be adequate. What do you guys think?
Thanks – Gary Froeschner
-- 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