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Out drive to shaft drive conversion?


W+T

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5 hours ago, W+T said:

Has anybody done the above on a GRP cruiser ?

 

What was involved and cost of parts etc.  I have the engine.

 

Admiral Faffer :)

Have thought of this,but dismissed it as alot of work for little gain.It won't reduce the draught but will get rid of the outdrive,and although I have never had a boat with one,word on the street is they are troublesome.Have a look at a Freeman, or a Creighton or any boat on blocks that has shaft drive,to give you some ideas.

My idea(which I dismissed as impractical) was to cut a strip about a foot wide and mould a tunnel for the prop in the stern.The prop would spin in the tunnel through a normal stern gland and be almost like jet drive.The prop depth would be much reduced.

Next time you see an old geezer in a pub with his pint staring into space,it could be me dreaming up impractical ideas for his boat.

By the way,regarding changing perspex for glass,put a straight edge across one of your front windows because I don't know about the Norman 32,but the Norman 20s front windows have a slight twist so making perspex necessary.

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Stern drive may be shallower draft than shaft.

Unless shaft drive was an option on the hull in question and therefore provision is or can easily be  made for mid engine mounts , the shaft etc and rudder I would imagine refurb of the outdrive is the easier option.

 

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Unless you opt for a V drive the engine will have to be moved a lot further forward. A V drive not so much but dealing with the stern gland can be difficult unless the V rive is a remote unit but then that will need to be a fair away forward.  You will need a stern gland assembly which will come with a brass/bronze plate attached so you cut a slot in the hull for the shaft, position the plate over it and bolt the plate in. Then glass over the flanges of the plate. Next comes an A pr P bracket to support the shaft just forward of the prop. Again it will come with a flange for bolting to the hull and glass over the internal nuts.

 

The bearing in the A/P bracket, the stern gland and the gearbox coupling all need to be in perfect alignment and as the A/P brackets come with the bearings set at a variety of angles this is not easy.

 

If you are lucky the hull just might have a keel with  a flat back end and large enough to fit the stern glad & rear bearing assembly that will be similar to a narrowboat  but without the length of tube. In that case you will probably need a pair of  angled distance pieces to get the shaft lined up with the coupling. Either very good quality marine ply or preferably a good hardwood is normally used. Again glass the fixings on the inside.

 

If its a wooden boat with a  keel don't even consider it, you will have to make & fit a shaft log on the inside and then bore it at the correct angle for the shaft.

 

Next you need a prop and shaft coupling.

 

As you have removed the steering you now have to fit a rudder. The easiest way may be to fabricate something to hang off the transom narrowboat style but if you want to keep with cruiser practice you need a complete rudder assemble with a flanged rudder tube. The tube flange is bolted to the hull, possibly on a wooden pad and the flange glassed over.

 

The good news is that you may be able to use the existing steering cable etc. The bad news is that getting teh shaft angle right is not easy and the cost is likely to be in the four figure range. I suspect Norris of Isleworth will list the parts so you can price them there.

 

28 minutes ago, MartynG said:

Shaft drive can be troublesome too.

A friend is replacing his drive plates. It's not too bad a job but not cheap.

Unless you get a proper marine engine that does not use a  drive plate then drive plates should be considered as consumable items and it is probably best to visibly check them every 8 to 10 years or so,.

23 minutes ago, MartynG said:

Stern drive may be shallower draft than shaft.

Unless shaft drive was an option on the hull in question and therefore provision is or can easily be  made for mid engine mounts , the shaft etc and rudder I would imagine refurb of the outdrive is the easier option.

 

Fully agree. I have explained what it would involve so the OP can think again.

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Page 18-19 (amongst others) of the attached may be helpful, the dimension drawings may give you ideas for DIY ?

 

https://www.lancingmarine.com/databook/databook.html?page=18

 

And, the prices :

 

https://www.lancingmarine.com/uploads/pdf/5af440e70f2e7_page42.pdf

Edited by Alan de Enfield
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16 minutes ago, Alan de Enfield said:

Page 18-19 (amongst others) of the attached may be helpful, the dimension drawings may give you ideas for DIY ?

 

https://www.lancingmarine.com/databook/databook.html?page=18

 

And, the prices :

 

https://www.lancingmarine.com/uploads/pdf/5af440e70f2e7_page42.pdf

Certainly a solution but it looks very unprofessional to me and vulnerable to damage. Swing that thing against something hard and I think there is a good chance the leverage would tear the transom out f the boat.

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5 minutes ago, Tony Brooks said:

Certainly a solution but it looks very unprofessional to me and vulnerable to damage. Swing that thing against something hard and I think there is a good chance the leverage would tear the transom out f the boat.

Agreed but if someone is trying to 'DIY' a boat to shafts on a hull not designed for them the work (as you have stated) is 'excessive'.

At least this allows for the engine to remain in the place that was built for it.

 

The possibility of 'knocking it off' could be minimised by building a 'railing / guard' around it.

 

As a generality - I think GRP boaters tend to be more aware of their boat size and have better spatial awareness (due to the fragility of their boat) that Steel boaters.

Edited by Alan de Enfield
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43 minutes ago, Alan de Enfield said:

Page 18-19 (amongst others) of the attached may be helpful, the dimension drawings may give you ideas for DIY ?

 

https://www.lancingmarine.com/databook/databook.html?page=18

 

And, the prices :

 

https://www.lancingmarine.com/uploads/pdf/5af440e70f2e7_page42.pdf

But adds to the boat length, so increases licensing and mooring costs.

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10 hours ago, Alan de Enfield said:

Page 18-19 (amongst others) of the attached may be helpful, the dimension drawings may give you ideas for DIY ?

 

https://www.lancingmarine.com/databook/databook.html?page=18

 

And, the prices :

 

https://www.lancingmarine.com/uploads/pdf/5af440e70f2e7_page42.pdf

 

Now tht i like the loom of, exactly what mite be what i am after, prices are a bit much though, but then i would like to make my own set up, love a bit of good old engineering aswell ;):)

 

 

 

 

10 hours ago, Tony Brooks said:

Unless you opt for a V drive the engine will have to be moved a lot further forward. A V drive not so much but dealing with the stern gland can be difficult unless the V rive is a remote unit but then that will need to be a fair away forward.  You will need a stern gland assembly which will come with a brass/bronze plate attached so you cut a slot in the hull for the shaft, position the plate over it and bolt the plate in. Then glass over the flanges of the plate. Next comes an A pr P bracket to support the shaft just forward of the prop. Again it will come with a flange for bolting to the hull and glass over the internal nuts.

 

The bearing in the A/P bracket, the stern gland and the gearbox coupling all need to be in perfect alignment and as the A/P brackets come with the bearings set at a variety of angles this is not easy.

 

If you are lucky the hull just might have a keel with  a flat back end and large enough to fit the stern glad & rear bearing assembly that will be similar to a narrowboat  but without the length of tube. In that case you will probably need a pair of  angled distance pieces to get the shaft lined up with the coupling. Either very good quality marine ply or preferably a good hardwood is normally used. Again glass the fixings on the inside.

 

If its a wooden boat with a  keel don't even consider it, you will have to make & fit a shaft log on the inside and then bore it at the correct angle for the shaft.

 

Next you need a prop and shaft coupling.

 

As you have removed the steering you now have to fit a rudder. The easiest way may be to fabricate something to hang off the transom narrowboat style but if you want to keep with cruiser practice you need a complete rudder assemble with a flanged rudder tube. The tube flange is bolted to the hull, possibly on a wooden pad and the flange glassed over.

 

The good news is that you may be able to use the existing steering cable etc. The bad news is that getting teh shaft angle right is not easy and the cost is likely to be in the four figure range. I suspect Norris of Isleworth will list the parts so you can price them there.

 

Unless you get a proper marine engine that does not use a  drive plate then drive plates should be considered as consumable items and it is probably best to visibly check them every 8 to 10 years or so,.

Fully agree. I have explained what it would involve so the OP can think again.

Just the kind of info i was after. Thanks Tony, again a cracking reply. 

 

 

9 hours ago, David Mack said:

But adds to the boat length, so increases licensing and mooring costs.

 

If i did do it i would not be paying much more at all. 

 

 

 

Well with all the info i have gathered i will think more on it. the main concern would be to clear the prop if it gets, well when it gets fouled. The surface drive will make this easier than adding also a weed hatch to a shaft drive.

 

.In the time its being rebuilt i an always save the money to rebuild the Transdrive it has, its said to be good but then i dont believe a thing a seller tells me. 

 

So watch the other sapce to see what i get upto :)

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12 hours ago, Tony Brooks said:

Unless the boat has a hollow keel I doubt you would be able to fit a weed hatch because of the need for the strong point mounting flange for the A/P bracket.

Reason looked into surface drive. If i do it. Which i doubt tbay will be the way

 But make it all myself from scratch.

 

Syaying as is untill i know how it runs this weekend amd a few trips out. See whay arebuild will cost of the transdrive  etc etc

 

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1 hour ago, W+T said:

Reason looked into surface drive. If i do it. Which i doubt tbay will be the way

 But make it all myself from scratch.

 

Syaying as is untill i know how it runs this weekend amd a few trips out. See whay arebuild will cost of the transdrive  etc etc

 

You need one of these Wayne. 

 

-diesel-outboard-engine-on-a-thai-longtail-boat.jpg

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It might be worth mentioning that every hull fitted with an outdrive, most hulls fitted with an outboard, and many cruiser hulls with shaft drive suffer from that dreaded condition known as the Immersed Transom.  That is the condition that causes such hulls to create a disproportionate disturbance of the water, wasting fuel as they go and waking up all those sleepy-headed continuous moorers.  Such hulls may perform well at planing speeds at sea but are dreadful on inshore waters.

 

Because I rely on electric drive the first requirement for any hull is a sleek shape, with the bottom of the transom as close as possible to the surface.  In my case I had to design and build my own.

e3.JPG

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12 minutes ago, Murflynn said:

It might be worth mentioning that every hull fitted with an outdrive, most hulls fitted with an outboard, and many cruiser hulls with shaft drive suffer from that dreaded condition known as the Immersed Transom.  That is the condition that causes such hulls to create a disproportionate disturbance of the water, wasting fuel as they go and waking up all those sleepy-headed continuous moorers.  Such hulls may perform well at planing speeds at sea but are dreadful on inshore waters.

Which is why most yachts (even super-yachts, not just sailing yachts) are 'canoe stern' (ie taper at both ends)

 

Image result for canoe stern yacht

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58 minutes ago, Alan de Enfield said:

Which is why most yachts (even super-yachts, not just sailing yachts) are 'canoe stern' (ie taper at both ends)

 

 

unfortunately that is not quite true. ...........  accommodation requirements have imposed themselves on ever shorter yachts (money saving) to the point that many do have a square transom, although not often deeply immersed - unless you classify 'motor-sailers' as yachts of course.  .....  and all modern top class ocean racing yachts have wide transoms that they can get away with because they are so fast that they act like planing hulls.

 

Double ended yacht hulls were the norm as long as boats were made from timber, until the 60's, with all the planks ending on a stem and a sternpiece (or having a schooner stern), however the advent of GRP allowed the designer to provide a huge aft owner's stateroom, to the detriment of sailing performance.  The joints involved in timber transoms on a yacht are just a potential source of weakness.  Suhaili is one of my favourite ocean yachts - she would go through a tempest and do a forward roll and come up smiling.  As you say - a canoe stern.  

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