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17 May 2014. Prop Problems (lesson learned)

© janice142

This week the engine is in and running well. Originally, when under load (in gear) she would overheat. There are several possible solutions but the one we are working with at present is that the thermostat has been removed. And now Robert no longer gets too hot -- at least when in neutral.

In Case You Wondered:  Robert is the name of my engine. When my friend Bob Winter sold her to me last autumn the name was supposed to be BOB but after a few issues (recalcitrant child!) I asked Bob what he was called when he was a boy. He said Robert, so the engine's name is Robert.

On Thursday (15 May) I started Robert for the first time solo.  The boys were away and my mechanics want the engine started every day. So I did -- without issue.  She ran beautifully and I was able to get the readings from my new hand-held tachometer and hand-held infrared thermometer.


Handheld Digital Laser Photo Tachometer RPM Tach Small Engine Motor Speed Gauge

For Mother's Day I gave me
two new toys tools for Seaweed:

Affiliate Links

Etekcity® Infrared Thermometer, Digital Temperature Gun,


Years ago, the Digital Tachometers ran $250 -- way above my budget but the prices have really come down. Ditto Digital Temperature Guns.  Now that they are affordable ($20 each, give or take) I bought my own set for Seaweed. 


For diagnosing stuff before it becomes a problem, the temperature gun will be useful. Apparently my manifold will eventually start to become restricted and then the temps will rise. When that happens it's time to clean out the manifold -- a simple fix, and far less money than the $1300 required to replace the one on my Volvo.

Reflective Strip on my flywheel. The hand-held tach counts revolutions via that strip.


Seaweed has a LH16x16 propeller. That means the prop is 16 inches in diameter and has a pitch (curvature) of 16. She is Left Hand -- means turns that way for forward propulsion. And, though that is fine for the old gasoline beast, my new Volvo is much smaller. Oh, and the shaft size is 1.25" and tapered.

To get the proper prop size, I used the
online calculator by Victoria Propeller:

The prop I have is too big. It is now stowed on the forward bulkhead in my bilge.

I have a 16x16LH and of course that's one of the common ones (selling for $200 or so, if you can find a buyer) BUT the one I need for the new Volvo is a left hand 16x8.5 or 14x10 -- available thus far at a cost of $500. That's a lot of $$, so I am shopping and trying to find one for less. Or something similar. It really doesn't have to be exact, but 16x16 is too big.

Thus, now I'm shopping for a 16x8.5 or 14x10 (or something similar) in a Left Hand version for Seaweed. I shall start looking again seriously on Monday as tomorrow is Sunday.


About Propellers, you need to know:


Sizing:  the shaft size of your boat is one component and you can only go up or down 1/8". The hub of your new propeller has to be within the 1/8" margin, larger or smaller in diameter.

That might sound confusing but it's not too. See this chart:

Smallest that will work:
1 and 1/8" aka 1.125"
What I have:
1 and 1/4" aka 1.25"
Largest that will work:
1 and 3/8" aka 1.375"


Thus my shopping allows a bit of wiggle room, but just a tiny bit. 
The hub (center of) the propeller can be adjusted 1/8" but no more.


Advice on used prop places appreciated.  And yes, I will update as soon as I have one on the way though I suppose having two would not be a bad thing -- if the price were fabulous.


Addendum 20 May: A lesson learned.


I started this quest for a used propeller with an easy attitude that this would be a cinch. After all, there are lot of propellers out there and I thought finding one could not be all that hard. Soon enough I was educated.

There are a lot of bad propellers out there, and often for sale. I checked various marine consignment shop across the country.  Part of the problem is the desired size. This is apparently not a common one.

But mostly it was quality issues that bit me.  Repeatedly I found in pictures curled edges, chipped blades, and worse.  Therefore if I cannot find one from a propeller place (versus marine consignment shop) well, I will have to spend my perfectly good money and pay retail.


This prop has gouges along the blade edges.

Prop was too large so someone cut off the
ends of the blades. Ugly, and for sale: cheap!

Painful financially but a better option in my view than spending $$ for a propeller, then reconditioning, plus re-boring. Those two items run (circa May 2014) between $200 and $250, and up. Plus shipping every which way ... well, I will be better off spending $500 for a new one.

Don't 'cha just hate spending that kind of money?!  I am rationalizing this as a one-time expense and will most likely sell my old 16x16LH for the weight in metal.

Lesson Learned:  Either buy directly from a propeller shop that has reconditioned/guarantees the prop, or bite the proverbial bullet and pay retail.


Final Update: A 14x12 left hand 3-blade propeller with a 1.25" bore has been located at a prop shop by my mechanic at Just Right Marine [http://justrightmarine.com]. It is being reconditioned/resized for Seaweed and for a sweet price.  The place is in Panama City, FL. [Yes, I'll post the name soon.]

Have you ever re-propped?
Any propeller replacement issues I should know beforehand?

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