You'll still have to lap the new prop hub to the shaft. Get some blueing or even just a sharpie to color out the area where the hub sits. Apply lapping compound and "screw" the prop on the shaft. Do about 10 turns, check if the sharpie is wearing off evenly. Repeat until the sharpie wears off evenly for the full length of the hub. Next, push the hub all the way on with no key and very clean shaft. Use a sharp tip (new) sharpie to mark the furthest point of the hub on the shaft. Remove the hub, install the key, reinstall the hub, verify that the key is not impeding the engagement of the hub on the shaft.
I had asked a machinist to install my prop thinking that he would understand the request as lap, key, fit, etc. When I picked the shaft up from the shop it seemed correct. Fortunately when push/pulling the shaft into the log and using the prop as a handle things started to get loose. I had to investigate and found the key was too tall (thick) and the hub had not been lapped to the shaft. I ended up needing to cut off about 5/8ths of threaded area. Imagine if I hadn't discovered this improper fit!? https://youtu.be/a5EbjgfklaI?si=7QHzilON4C6p4G9P https://youtu.be/Yl_kogi9uhg?si=hZ0M8UsFn-7EV33h https://www.dropbox.com/scl/fi/5yelipqph1fct0ysen4vi/1348adf46dcaded57ff03ee2f10649d50368c7c9-and0.jpg?rlkey=j6f75iq7r8sis2hn45oo7a3yx&dl=0 All the best, Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD Oct 7, 2025 20:35:22 Eddie Wills via CnC-List <[email protected]>: > Hey all - thanks for the input. > > Note that Martec is out of business and there are no engineering drawings > available on the internets. The martec-props website is a company in AZ that > refurbishes old Martec props and retails Aussie Slipstream folding props. > > …So I ‘crowdsourced’ the answer from a series of eBay listings, and based on > the measurements in the photos it looks like ‘Standard’ Martec taper is 1/16 > ratio. > > GPT told me a different answer- Which I will not repeat here in the interest > of avoiding generation of fake GPT wisdom. > > In the end, I bought the Flex-o-Fold prop. If I find out the Martec > measurements are different when I haul-out (in a few months) I will post an > update here. > > -Eddie W. > > > On Mon, Oct 6, 2025 at 1:55 PM Joel Aronson <[email protected]> wrote: >> Word of caution-some shafts have a left hand threaded nut. It’s happened to >> me twice! >> >> Joel >> >> >> >> On Mon, Oct 6, 2025 at 4:53 PM Peter W. via CnC-List <[email protected]> >> wrote: >>> I installed a max prop (2 blade) . I don’t recall the taper of shaft to be >>> of special note. I did have to cut off the shaft end . >>> But not very much. >>> Pete w >>> Siren Song >>> ‘90 C&C 30-2 >>> Irvington va >>> >>> Sent from my iPhone >>> >>>> On Oct 6, 2025, at 4:41 PM, Pete Shelquist-comcast via CnC-List >>>> <[email protected]> wrote: >>>> >>>> >>>> Eddie - >>>> Flexofold didn't ask me this when I bought mine, but that was a long time >>>> ago. It's held up really well btw. >>>> >>>> Couple suggestions; You could pull the existing prop and measure the shaft >>>> with a caliper and do the calcs. Or call martec and ask them what specs >>>> they manufacture to. They've been around long enough to have input on >>>> what's standard. >>>> >>>> Hope that helps. >>>> ---------------------------------------- >>>> *From:* ejwills1993--- via CnC-List <[email protected]> >>>> *Sent:* Monday, October 6, 2025 3:32 PM >>>> *To:* [email protected] <[email protected]> >>>> *Cc:* [email protected] <[email protected]> >>>> *Subject:* Stus-List C&C 30 Mark II - Shaft Taper? >>>> >>>> >>>> Hey C&C Sailors - >>>> >>>> I’ll be replacing my fixed Martec prop with a folding 2-blade prop this >>>> winter when it’s time to haul out. >>>> >>>> I’m being asked by Flex-o-Fold what my ‘Shaft Taper’ is. According to the >>>> boat user manual the taper is ‘standard’ but my understanding is that >>>> ‘standard taper’ can mean 1/10, 1/16, or 1/20. According to Flex-o-fold >>>> they need this shaft taper info for the correct adapter sleeve. >>>> >>>> The following info applies: >>>> >>>> -=-=-= >>>> >>>> 1. Boat - Make and Model C&C 30, Mark II >>>> >>>> 2. Engine - Make and Model - Yanmar 2GM20F >>>> >>>> 3. Transmission Reduction Gear Ratio - 2.62 : 1 >>>> >>>> 4. Displacement (Weight) 8300 lb >>>> >>>> 5. Water Line Length 25.75 ft >>>> >>>> 6. Shaft Size or Sail Drive Model - 1 inch conventional shaft >>>> >>>> 7. Propeller Rotation left hand or right Hand - Right Hand >>>> >>>> 8. Current Propeller Size and Type (i.e. fixed 3-blade, feathering, >>>> etc...) Martec RH 15D x 11P X1 (photo attached) >>>> >>>> >>>> I have also attached photos of the shaft drawing (from user manual) and >>>> Martec fixed prop. >>>> >>>> Martec Prop Photo[https://photos.app.goo.gl/tWbUW7CscPQz38MZ7] >>>> https://photos.app.goo.gl/tWbUW7CscPQz38MZ7 >>>> >>>> Shaft Diagram Photo[https://photos.app.goo.gl/WwZiFewzcUVDwdL87] >>>> https://photos.app.goo.gl/WwZiFewzcUVDwdL87 >>>> >>>> Thanks! >>>> >>>> >>>> -Eddie Wills >>>> >>>> C&C 30 Mark II ‘Mystic Star’ >>>> >>>> Your contributions help pay the fees associated with this list and help to >>>> keep it active. Please help by making a small contribution using PayPal >>>> at: https://www.paypal.com/paypalme/stumurray All contributions are >>>> greatly appreciated. >>> Your contributions help pay the fees associated with this list and help to >>> keep it active. Please help by making a small contribution using PayPal >>> at: https://www.paypal.com/paypalme/stumurray All contributions are >>> greatly appreciated.
Your contributions help pay the fees associated with this list and help to keep it active. Please help by making a small contribution using PayPal at: https://www.paypal.com/paypalme/stumurray All contributions are greatly appreciated.
