My propellers are on the wrong way round

[roywillson]

I own an Amerglass AK 32 running twin Perkins 4-236 engines and 2to1 paragon gearboxes I am replacing the propellers and have been told that my propellers are on the wrong way round.
My starboard turns anti clockwise the port clockwise when looking from the stern so they both turn into the centre of the boat.

I can rectify this but it means swapping over the gearboxes which is not an easy job how much difference would there be in the running of my boat if I leave them as they are or swap the gearboxes so that my starboard turns clockwise and my port anti clockwise.

I have checked the gerboxes when forward is selected and they both indicate forward on top of the gearboxes

 

[Doug_Stormforce]

Im not familiar with your boat but assuming its twin shaft, the starboard engine should indeed spin anti clockwise when in forward and the port clockwise when in forward.

This set up will make your close quarter handling infinaitly easier. When you put the starboard engine into forward it will not only pivot the boat to port but drag the stearn to starboard therefore improving your turning capabilities.

When in astern the starboard engine should then spin clocksie, dragging the stern to port and pivoting the sten to port, again everything is working together.

The port engine obviously does the oppisite.

Your shafts therfore are spinning the right way. It may be that the props themselves could do with switching over as there respectice shaft spin opposite directions. This is a much easier job and is probabally descibed if you do a search on the PBO forum

 

[Chris_d]

No they are correct, inward turning props are more desirable because the low speed handling is better, less paddle wheel effect when engaging reverse, and they also allow you to run on one engine with less correction required.
However inward turning props are not common because they require the shafts to be placed quite far outboard so that the prop wash does not interfere with each other.
Outward turning props seem to be more common on modern boats, because the packaging of the accomodation means the engines are generaly mounted closer together, so inward turning props will not work well.

 

[PCUK]

Sorry, Conventional wisdom says that props should always be outward turning to prevent them drawing air down into the water flow. However, as they have never given a problem in this respect, leave them well alone!!!

 

[jimg]

Chris_D is probably right, this is a boat that normally operates at displacement speeds.

 

[Chris_d]

Conventional wisdom used to say the world was flat. Obviously not all hulls are suitable and they are rare, but they are desirable for some boats, thought I said that though.

 

[Andrew_Fanner]

Fellow club member owns one (unusual but pretty boat) I'll ask him which way his turn if I see him this weekend.

 

[roywillson]

Thanks for the current replies most useful but always willing to listen to anyone's else's suggestions it all helps.

Andrew_Fanner I have owned her for four years and am yet to see another one in the water so would be greatful of any information on the Amerglass boats if your club member has any I have very little information on them.
Cheers

 

[jimg]

Used to be one in Bristol Harbour, not sure if it is still there....

 

[Andrew_Fanner]

PM sent

 

[pheran]

Used to be another one, moored on the Thames at Abingdon, about a quarter of a mile downstream from the bridge. It was there for years.

 

[Wiggo]

Well, if you swap the props, you'll have to change the gearshifts around to run the boxes permanently in reverse to compensate for the prop swap. Some boxes don't like this (it can bugger up the internal lubrication) and some have different ratios astern. Leave well alone unless you really want to take both boxes out.

 

[macnorton]

either way is ok.
turn out = low speed better control
turn in = high speed craft (lifts the stern)

I read this in MBM a few years ago.

 

[alb40]

My props are also set up as inward turning. The gearboxes both run as per engine rotation, so one of my engines turns in the opposite direction to the other.

Changing that would mean swapping the engines round, but the boat has had them set up like that from new, there is no problems caused by it. Enjoy your boat rather than trying to fix a problem when there isn't one!

 

[roywillson]

I must admit leaving well alone is my idea as well, I haven't noticed any problems over the last four years just that the guy making my new props suggested it would be better to swap them over

Both my engines are left hand rotation so I have got a left and right handed gearbox so it would only need the gearboxes changing over

I am intending to lift both units some time in the future to replace all the engine and gearbox mounts so will try swapping them then two jobs in one and will be able to compare performance new props and the different rotations

Just need a season without two many expensive problems to get the mountings done