Turning Clock or anti clock wise

Thanks Manie, I also thought it worked out quite well. Lucky that with a brushless motor drive, one can optimize the revs with the prop by manipulating the Pulse width in combination with the supply Voltage. I hope to have, after 2 years, the motor ready by this year April. How are you doing?
Bert

 

Bert I am good, just the work seriously distrupts my life.
The lack of time is just plain lousy.
Anyway you must get your boat to the water, as you may have read my little excursions are the "golden" moments of my life http://www.boatdesign.net/forums/boat-building/manies-microcruiser-27869-53.html#post607250
Building and designing - like where you are at now, is fantastic - but when she hits the water your life changes.
So my 2 cents - get her to the water - the details can be sorted later.

 

O.K. Manie, I will try to finish it off. But you think you have no time, I am already retired since my 55 and it seems that I have less and less time for my hobbies. I will be flying to Joie this week to be at my daughters birthday. To drive, it is too far in one day. Again 4 days no work done on my hobby. But I agree, to be on the water is a pleasure and great fun, whether on a cruise liner or on a rubber dinghy. .
Bert

 

Stainless will "weld" to itself in seawater? Did he mean galling when installing the bolts? Stainless is very prone to galling. copper grease is commonly used to reduce friction and avoid thread damage when installing bolts.
"Stainless steel" covers a very wide range of materials with an equally wide range of properties. I have seen all types of failures from corrosion, pitting, etc, but am not familiar with what you described.

 

Thanks John.
Well, he mentioned that often when he got a repair job and twee SS materials were used without copper grease between it, he was struggling to separate them. Special if SS bolts were used in a SS thread. Maybe some other forum members can comment and see what their experience is. He gave me a small bag with copper grease to use when I mount the prop permanent. It could be that often SS 304 bolts are used on 316 plates. I love to hear what the experience is from other members. Bert

 

OK, that sounds to me like galling of the threads. If the bolts are heavily torqued, it certainly can be an issue with stainless. The seawater is not a factor.
here is alink to a description:

http://www.greensladeandcompany.com/pdf/Problem Solving-Stainless Steel Galling Solutions.pdf

 

Thanks for the article, interesting to read. One is never to old to learn something. He also advised me to put the copper grease between the prop and the shaft. Both metals are 316 and we will thus have some oxidation layers.
Bert

 

Copper grease (Molykote) works like a charm. No galvanic action because the copper particles are surrounded by grease, so the stuff doesn't conduct.
It turns a bit darker brown after a prolonged stay in the sea, but that's only superficial.

 

Thanks CDK, but does it mean,should I use copper grease between the prop and the shaft, that my galvanic system will be interrupted and the prop will start being eaten away, while the shaft is protected by the zinc, which is mounted on the shaft and thus makes electric contact? Refer thread 44 - 3019.jpg
Bert

 

I don't think you need it between your prop and the shaft, because that's another situation respect to bolts or screws. The cold welding can happen when two conditions are met:
- there's a high friction or fretting between parts in contact, which scrapes off the protective oxide layer and leaves areas of pure metal exposed;
- there's a sufficient pressure pushing two parts onto each other.
Both conditions will happen on the threaded surface of fasteners, but imo not in the contact area between the prop and the shaft - where relative motions are negligible and contact pressure is many times smaller. However, this is just my opinion - so hear what others have to say on that regard too.
Cheers

 

Thank you daiquiri, I value your opinion and will only use copper grease at the front on the large nut and bolt, and not on the shaft/bush itself. I do however have to use it also on the M8 bolt which transfers the torque from shaft to prop. Thanks all, what would I do without this forum.
Bert

 

I fully agree with daiquiri
I would however use a touch of copper grease on all surfaces when assembling

I use the stuff almost every day, on our engines all sparkplugs get it as well as head bolts and exhaust bolts.
I have used it on stainless SHAFTS and bolts

My bottle is now 8 years old and is still half full, you only use a smidgen on your finger tip at a time.
I KNOW the stuff works. Have used it for 35 years in total.

 

I concur with Manie here. The copper grease performs two jobs: it lubricates the mating surfaces of stainless bolts and nuts during tightening and fills the voids on the opposing sides to prevent capillary action.

A splined outboard prop can be removed by hand if the splines got a smear during assembly; if it was installed dry you need a puller. On a tapered shaft you need a puller anyhow because there is at least one spot of metallic contact, but the force needed to separate the parts is much less.

 

wow with that shape infront of the propellor the must be some terrible water turbulance and disturbance dont you think ??
I used to spend hours doing prop apatures on Yachts and fairing and sanding and glassing and sanding and polishing etc etc 90% had 3 bladed props but now and then a 2 blade would come on the scene and the shaft would get marked so the blade stood vertical for less water drag .Surely a glass shape even as a cover to form a nice lead into the prop would helpa lot with its efficency and smoothness ,Two blades are nitorious for vibration and noise in a case like that .

 

I agree, the turbulent wake behind such a thick skeg will create additional drag, will significantly decrease the propeller efficiency and may create vibrations (depending on the power input).
Judging from the picture, the skeg hides nearly half the propeller disk from the clean inflow. But looks like it's too late to modify anything at this stage, so Bertku will have to live with it...