Prop Shaft Locking Device?????

[ron6785]

Has anyone found a really good way of easily locking down one shaft when underway, that is easily removed. I will be traveling with some trawlers this winter and so at 7-8 knts one engine is sufficient and I want to be able to switch engines during the day.

I've successfully used rope and pipe wrenches when I've only had one engine, but they arn't the answer for regular use.

I know we've discussed this but can't find it.

Thanks, Ron

 

[MicroKap]

I think it was discussed that there were no major savings in fuel use for using one engine and locking the shaft on the other because of the drag created by the stationary propeller and the offset to the rudder in order to steer straight.

 

[REBEL]

A big pair of vise-grips on a coupling bolt (preferably a nut) beats a pipe wrench. Lock them on so that the rotation tries to "tighten" the bolts instead of loosening them. rebel

 

[Will]

Locking one shaft and running on a single engine makes little difference as far as fuel savings is concerned but doing so enables you to run a single engine closer to temperature and load recommendations. If you intend to do a lot of it, you might go as far as to get another set of props sized for single engine operation and install shaft breaks. Shaft breaks are like disk brakes designed to work on prop shafts. BIG BUCKS.
Will

 

[ron6785]

I think it was discussed that there were no major savings in fuel use for using one engine and locking the shaft on the other because of the drag created by the stationary propeller and the offset to the rudder in order to steer straight.

Yes, I remember that conversation, and I know I wouldn't double the mileage, but again I'll be traveling at below hull speed so there should be some savings as even with one engine,at those speeds ,it won't be under a great load.

I'm actually trying to increase my cruising range and so it's worth a try.

 

[REBEL]

Locking one shaft and running on a single engine makes little difference as far as fuel savings is concerned but doing so enables you to run a single engine closer to temperature and load recommendations. If you intend to do a lot of it, you might go as far as to get another set of props sized for single engine operation and install shaft breaks. Shaft breaks are like disk brakes designed to work on prop shafts. BIG BUCKS.
Will

Those a great, but not a bolt on job. IDEALLY, the brake needs to be keyed to the shaft. If not, when (WHEN!) it slips, it will set you up for a nice stress fracture, not to mention the galling when you try to remove the broken shaft. My shrimp boat with 8-71s and allisons has this and we run on one engine for temps and speed. That 3 inch shaft was adoozy to replace. rebel

 

[Pascal]

tie a short line on the shaft with just a short loop sticking out. then tie another line to an engine mount or something sturdy and hook that in the short loop with a heavy clip. dont' understimate the torque these props will pull at 7kts!

also, 7kts on a one engine is fine, 8kts an over you may be increasing the load on the engine. single engine trawlers are propped and geared for single engien ops, not a twin Hatt.

 

[TopHattandTails]

why not just sleep in an hour later and arrive together?

 

[ron6785]

why not just sleep in an hour later and arrive together?

Well in fact we do that quite a bit with a couple we cruise with. This is going to be about 4-5 boats going to the Bahamas, Puerto Rico, Dominican and BVI's, and as mentioned doing it more to extend my range.

 

[ron6785]

tie a short line on the shaft with just a short loop sticking out. then tie another line to an engine mount or something sturdy and hook that in the short loop with a heavy clip. dont' understimate the torque these props will pull at 7kts!

also, 7kts on a one engine is fine, 8kts an over you may be increasing the load on the engine. single engine trawlers are propped and geared for single engien ops, not a twin Hatt.

Thanks, I've done something similar to that, but want the ability to easily alternate engines and also the ability to disconnect when under way easily should I need both engines. What kind of gear reduction do the 58LRC's have??

 

[ron6785]

Those a great, but not a bolt on job. IDEALLY, the brake needs to be keyed to the shaft. If not, when (WHEN!) it slips, it will set you up for a nice stress fracture, not to mention the galling when you try to remove the broken shaft. My shrimp boat with 8-71s and allisons has this and we run on one engine for temps and speed. That 3 inch shaft was adoozy to replace. rebel

I've got 8-71n's, what allisons do you have?(m20). Do you get better fuel ecomomy or can you tell??

 

[captddis]

tie a short line on the shaft with just a short loop sticking out. then tie another line to an engine mount or something sturdy and hook that in the short loop with a heavy clip. dont' understimate the torque these props will pull at 7kts!

also, 7kts on a one engine is fine, 8kts an over you may be increasing the load on the engine. single engine trawlers are propped and geared for single engien ops, not a twin Hatt.

I have done this a number of times with good results. I did have a 5/8 piece of braided line chafe and break. The third day I found a diver to pull the prop.
No difference in speed but the boat felt better.

 

[Freeebird]

Well in fact we do that quite a bit with a couple we cruise with. This is going to be about 4-5 boats going to the Bahamas, Puerto Rico, Dominican and BVI's, and as mentioned doing it more to extend my range.

OK, y'all know I had to chime in on this one. If you're doing it to increase your range, forget about locking the shaft and pull the prop. You WILL get extended range by doing that... been there, done that on a 1,000+ mile run. Compared to locking a shaft, this will give you more speed, more range, and less drag which will pull you toward the side of the non-running engine.

 

[rsmith]

Technicly you might need to comply with these regs


A vessel restricted in her ability to maneuver, except a vessel engaged in mine clearance operations, shall exhibit:

(i) three all-round lights in a vertical line where they can best be seen. The highest and lowest of these lights shall be red and the middle light shall be white;
(ii) three shapes in a vertical line where they can best be seen . The highest and lowest of these shapes shall be balls and the middle one a diamond;
(iii) when making way through the water, a masthead light or lights, sidelights and a sternlight, in addition to the lights prescribed in sub-paragraph (i);
(iv) when at anchor, in addition to the lights or shapes prescribed in sub-paragraphs (i) and (ii), the light, lights or shape prescribed in Rule 30

 

[ThirdHatt]

Thanks, I've done something similar to that, but want the ability to easily alternate engines and also the ability to disconnect when under way easily should I need both engines. What kind of gear reduction do the 58LRC's have??

That is the reason NOT to remove a prop. You will get increased range running while on one, but the minor additional increase from removing a prop is insignificant and is certainly not worth losing the ability to quickly and easily go back to twin screw. You will also want to alternate which engine you run on as you stated earlier.

Good Luck and Have Fun! GIDDYUP!

 

[REBrueckner]

Here is how I locked a shaft that worked best for me: This was a 1972 Hatt YF with 8V71TI's....I could not discern any reduction in fuel use and maneuvering was restricted underway but not intolerable. I did not do this is heavy seas but rather calm weather and seas.

I used a piece of hardwood cut to fit between a shaft/tranny flange bolt and the engine bed strionger maybe 15" away. I just placed the hardwood piece with one end against the engine bed stringer and turned the shaft flange by hand until a bolt head was wedged against the opposite end. Pressure from forward motion held the piece in place and to disengage the stop I simply started that engine, put in in reverse for a moment, and the wood fell to the bilge out of the way. As I single hand, this flexibility was important to me.

You can also form a tiny VEE shape at the flange bolt end of the hardwood to assist in keeping the wood stop in place, but after some cruising hours I recall that depression being formed from rotational pressure. Of course you cannot operate the boat in reverse as the stop will likely fall out of place.

I used a spare piece of wood I carry aboard....I guess if you do this in advance, using a piece of steel would avoid any wear on the end.

edit: Based on my own observations and reading prior discussions on this subject, I decided it was basically a waste of time for my normal cruising.

 

[scary]

Thanks, I've done something similar to that, but want the ability to easily alternate engines and also the ability to disconnect when under way easily should I need both engines. What kind of gear reduction do the 58LRC's have??

Which engines, 4-72/6-72. The 48 has 3-1 reduction. With the 58 if you slow to 6knts isn't your range going to be greater 3000knm.

 

[ron6785]

Here is how I locked a shaft that worked best for me: This was a 1972 Hatt YF with 8V71TI's....I could not discern any reduction in fuel use and maneuvering was restricted underway but not intolerable. I did not do this is heavy seas but rather calm weather and seas.

I used a piece of hardwood cut to fit between a shaft/tranny flange bolt and the engine bed strionger maybe 15" away. I just placed the hardwood piece with one end against the engine bed stringer and turned the shaft flange by hand until a bolt head was wedged against the opposite end. Pressure from forward motion held the piece in place and to disengage the stop I simply started that engine, put in in reverse for a moment, and the wood fell to the bilge out of the way. As I single hand, this flexibility was important to me.

You can also form a tiny VEE shape at the flange bolt end of the hardwood to assist in keeping the wood stop in place, but after some cruising hours I recall that depression being formed from rotational pressure. Of course you cannot operate the boat in reverse as the stop will likely fall out of place.

I used a spare piece of wood I carry aboard....I guess if you do this in advance, using a piece of steel would avoid any wear on the end.

That sounds like an easy fix. I'm curious when you were using only one engine were you attempting to run at the same speed as with both engines. I can see that with 8/71 naturals trying to run at 9-10 knts I would load the single engine up and fuel saving would be negligible, however we're talking about 7 knts and the engine would have approximately the same load as when I'm going 8-10 knts. with both

 

[ron6785]

OK, y'all know I had to chime in on this one. If you're doing it to increase your range, forget about locking the shaft and pull the prop. You WILL get extended range by doing that... been there, done that on a 1,000+ mile run. Compared to locking a shaft, this will give you more speed, more range, and less drag which will pull you toward the side of the non-running engine.

As we all know you have alot of experience running on one engine, what type of fuel usage did you experience with one engine, or did you keep track?? I don't want to pull the prop as I will be traveling in the Atlantic and the Carribean and want to be able to use both engines when needed. Again, the only reason for one engine is to extend my range. It appears, based on comments here, that there is very little if anything to be gained from a fuel economy standpoint in running on one engine.

 

[ron6785]

Which engines, 4-72/6-72. The 48 has 3-1 reduction. With the 58 if you slow to 6knts isn't your range going to be greater 3000knm.

I don't have a LRC, I have a 53MY with 8/71 naturals. Since with these naturals the boat would never plain, I really don't know why they didn't put 6/71 or 4/71's in these boat as they would push the boat to hull speed at a much greater savings in fuel. I carry 550 gallons of fuel so you can see my reason for trying to extend my range.

There are of course other options, like a fuel bladder, but they arn't a particularily good option for a motor yacht.