79 H30 with Yanmar YSM12 Prop recommendations?

[Ben Jammin]

I have a 1979 Hunter 30 with the original YSM12. The 3-bladed prop on it is badly corroded and needs to be replaced. I have not actually driven this boat under power, since the engine wasn't running when I got it. I should have gotten my diver to look for size numbers on it, but I didn't think of that. A typed sheet in the back of some manual that I downloaded lists 13x13 for a 30', but then says 1979 13x 10. It also quotes a rule of thumb to drop 2" in diameter and keep the same pitch when going to a 3-blade. The Yanmar service manual says 13x8-1/2 3-blade (if I'm reading the table correctly).
So I'm looking for any recommendations on size, pitch, number of blades, and maybe brand. I don't have budget right now for any cool feathering props, in fact I'll be looking for something used to begin with (since its a LH, that could be tough).
Ben

 

[Jalepeno]

I'd recommend looking at a Campbell Sailor propeller. I use a three blade CS3LH12x7x1 with YSM12 (1.98:1 reduction ratio). I suspect you would use as similar propeller even though my boat is a bit lighter. Look them up on the internet and email or call them for sizing and price.

 

[David in Sandusky]

First, in our experience the Campbell Sailor is the best fixed blade prop you can buy. I would stick with the original/standard diameter (sounds like 13.) the diameter is about fitting the prop to your boat Then let West by North who make the prop determine the pitch from you displacement, and engine. The pitch is what determines the transfer of power from the drive train to the water, and that is the manufacturer’s expertise.

 

[ggrizzard]

The original prop on my H30C was a 2 blade mated to the YSM 12.
I suspect the PO of your boat changed the prop to get more umph out of an under powered engine (for the boat size and weight).
I re-powered with a 2GM20 and a three bladed prop. Now I do 6.5 kts at 2700 RPM.

 

[Ben Jammin]

Today I called West by North and left a message, and also filled out their online propeller recommendation form. The problem is that I need a prop within 2 weeks for getting to a boatyard for a haul out, then 50 miles to my new slip. I suppose I could try to get to the boatyard with the current prop (I have BoatUS), since it's only like 15 miles, all in San Diego Harbor.
Ggrizzard, do you happen to know the pitch of the original 2-blade? A 2GM20 swap sounds good, but I have other issues to consume my time, money, and energy for now, and the old thumper is still kicking.

 

[ggrizzard]

Yeah Ben, I understand. And sorry, I gave the prop to the new YSM 12 owner when I sold it. Perhaps someone else still has the prop and can measure for you. Or, can you call Minnie's and see if they have a used prop for a 1" shaft?

 

[dLj]

If I was going inexpensive on replacing that prop, and wanted to stay with the three blade prop, I would simply use an epoxy, fill in all the bad locations on that prop, use it as a mold and cast a new one. I don't know if you have access to machine tools (lathe, mill etc.), if you don't, then that may be not so cheap. If you do, that could be a inexpensive way to get a brand new prop. That's what I did on my last boat, in fact, I cast two so I'd have a spare.

The original prop was actually missing one whole blade.

dj

 

[Ben Jammin]

Oh yeah, I should have thought of Minney's. So they have actually catalogued all their props on their website now, http://www.minneysyachtsurplus.com/used-propellers.html. But alas, nothing in a 1" shaft, left hand rotation, and within an inch of 13" diameter except 2-bladed props, and with a lower pitch (but not much). Well, for $65 and a drive up to Newport a 2-blade might make a good plan B if nothing else pans out. How do you know about Minney's, have you spent some time in SoCal?

dLj, I don't know many people who would put the word 'simply' in front of "use is as a mold and cast a new one." I assume you mean use it as a master to make a mold (plaster, sand?). I do have access to machine tools, but casting seems like a whole new ball of wax (if investment casting, pun intended). Seriously, I've never done any casting myself, is it really that simple?

 

[Ben Jammin]

By the way, one of the things I was hoping to find out from other Hunter 30 owners is what pitch works well with the 12hp engine. I'm hoping to find something that is off-the-shelf, rather than custom made, at least for now.

 

[Ben Jammin]

I just got off the phone with West by North and ordered a 12x8 LH Campbell Sailor. $600 (incl shipping) is more than I wanted to spend, but having confidence that I won't have to worry about it is probably worth it. And it sounds like they'll be able to get it to me in a couple weeks. Now I'm just worried about the ancient Yanmar throwing a rod a week after I get the new prop on there, then having to re-power with a RH rotation!
The casting idea is interesting, as I'm somewhat of a maker-type, but I just don't have the bandwidth right now to learn how to cast something, and I don't know of any DIY foundries around here...

 

[dLj]

Oh sorry, I didn't mean for you to do the actual casting, but rather send the prop to a foundry where they can cast it for you. One of the most expensive parts of casting is making the model, or pattern. But essentially you already have the pattern with your current prop. So you can use that. Talk to a foundry that can produce bronze castings and see what they need from you. Ask them what the typical shrink is for the alloy you want cast and you can then modify your prop using some kind of filler. I typically use an epoxy with filler because it easy to work smooth, sticks well the your current prop. Just easy enough to work with. You could also use like body filler used for car body work - just needs to stand up to handling to make the molds.

I'm currently traveling, won't have much internet access for the next two weeks. But after that if you are still interested in pursuing doing your own cast prop, drop me a note.

dj

 

[ggrizzard]

Ben... No, I've just been on this forum since 2004!