J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Folding Props

I don't know if it would disqualify the OD rating, but I would certainly be happy to race against you. That's a lot of drag.

The boat is manageable with the Martec. Also, as you compare it to your prior experience, remember that the underwater profile of the two boats are likely very different.

The prop wash throws a lot of turbulence across the transom hung rudder on the J30 and I think that's what causes a lot of the issues. I don't see a three blade prop helping that.

My advise would be to practice with the folding prop and figure out how the J30 likes to back up. Before you can apply steerage, you need a little aft momentum, so bump the throttle. Once the boat is moving back, bring the throttle to neutral to eliminate the prop wash. Don't throw the rudder over, it'll just stop the boat. With the big rudder on the very back of the boat, small movements will really turn the boat.

Please don't go with a three blade prop!

Yes it would be contrary to class rule 5.13.3 which states "Propeller, shaft and strut shall be in accordance with the standard installation with a propeller diameter of not less than 356 mm." You can see the standard installation in the diagrams at the end of the class rules.

You do remove the prop and send it back to Martec for reconditioning. They are very responsive. Here is the web link: http://www.martec-props.com/refurbish.htm

[This message has been edited by Rhapsody #348 (edited 09-26-2008).]

After 25 years Vee Jay got its new prop today ... but once every 25 years is pushing it. Interestingly the old key seems to be made of stainless and one end of that key was starting to look like swiss cheese.

At the other end of the shaft into the transmission it also seemed to have the same SS material for the key and that was just about falling apart.

They shipped a bronze key with the new prop ... so we are thinking of putting a bronze key at the other end of the shaft as well.

You would think that SS on a SS shaft would be good. But Martec is really strong about using Monel cotter pins ... so I gather SS keys may not be a good idea.

Also down here they automatically paint props on most boats.
Don't know why and don't like that idea.

mentioned somewhere above was that the new Martec prop's blades do not touch ... I never remembered the old prop not touching. But then I can't remember if I took all my pills this morning.

new illustrated here in max closed position:

Vic - is that a new prop or refurbished? Martec refurbished mine for about 1/3 the cost of a new one and it came back looking great. The blades did not touch after the refurb. They rewelded the stops, overdrilled the pivot pin hole, machined new edges and polished it like a mirror. It works great.

new ...

at its every 6-7-year refurbish, the original prop had its third shot at rehab 3 years ago [at the 22 year mark] ... but Martec had drilled it out to the max with max pin size ... problem seems to be drilling out the hub so that the holes for the monel pins get too close to the oversize pivot pin. at 21 years Martec cleaned it up and said: "don't send it back".

blade edges are knive sharp ... and nicked, probably from hitting coconuts.

I would be really surprised if your prop is the original.

on 526 the blades had stress fractures so now I have a spare hub with no blades. boat here is in water year round so don't have too much chance to pull prop, send it off for a couple of weeks. At the slip we have boats that run AC and all kinds of other stuff so I may be getting some stay electrolysis depending on who is around me.

It probably would help if these guys down here didn't paint the prop automatically when they do the bottom paint. told them to leave it alone this time.

The blades should not touch. The gap is what allows water to flow through the prop so it open properly. If the they touch and the prop spins it can just cavitate and not open.

1. photo of 25-yr-old 505 blade touching ... only symptom I've had with this prop is chatter on tight turns. Blade tips pretty much touching like this for past 4-5 years. also note blades are misaligned by about 1/3 in. as the pin holes are worn. and blade position sloppy



2. Photo of drilled to max pin ... problem i think is location of monel keeper pins if they drilled out this more. note the slop.



3. Photo of SS key used at the prop last time it was remounted.
serious erosion ... also key at the transmission flange on the prop was also SS and crumble city. Used bronze this time ... will update in seven years to see if the bronze works better.