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>> Home > Forum > Building Related > replacing propshaft
replacing propshaft
(864 views)
Author Message
RichardSReade
(Sub-Lieutenant)





Forum Posts: 45
22nd Dec 2017 11:33  
>> Permalink
mdlbt.com/36817

Hi all I have taken the bull by the horn and removed the 4ba prop-shaft, which was remarkably easy first using a stanley knife on the keel each side of the shaft and then as I was advised by a forum member to use mole grips, which I did, wallah out came the shaft, now as can be seen by the photos the new one, ( it is too long by an inch, Doh I ordered the wrong one) is a smaller diameter than the old one. What is the best way to refit it? Also using the keel as my straight edge, the shaft is at 9 degrees, is this going to be OK, also I am replacing the 54mm 3 blade prop for a 40mm so with the 850 motor I hope this will be sufficient.


Attached Files - Click To View Large


enjoyment is important.
ChrisF
(Sub-Lieutenant)





Forum Posts: 42
22nd Dec 2017 19:46  
>> Permalink
mdlbt.com/36837

What boat is it again Richard? As regards the prop shaft angle that is brilliant, the flatter the better. I aim to get around 12 degrees but you can go a little steeper.

That's a handy tool you have there.

Chris


Concentrating on the fine Fairey Marine boats
jarvo
(Fleet Admiral!)





Forum Posts: 550
22nd Dec 2017 21:08  
>> Permalink
mdlbt.com/36843

HI Richard, one way would be to slide the new shaft inside the old one, just need enough to fill the hull hole, sods law the outer old tube is to small!!!
The angle tool in your photo, where did you get it and what is it called????
Mark


Etherow Model Boat Club
RichardSReade
(Sub-Lieutenant)





Forum Posts: 45
22nd Dec 2017 22:01  
>> Permalink
mdlbt.com/36847

Chris, the boat is the Sea Commander, a boat my late father started in the 60's and I got to grips with it in 2015 but only floated it this year.
Mark, I have just got in from the workshop and saw your comments, well guess what, after shortening the new shaft by an inch and running a 4mm die down the inner shaft and trimming it to suit, I had a brainwave, why don't I try to fit the new shaft inside the old tube which would solve the problem with the hole in the hull and keel, so I cut the old one to the required length and tapped the brass bush from the end, the inner diameter of the old tube was too small, so on the lathe with it and fed a drill down it from both ends, as I did not have a drill long enough, so the old tube is in place and the new shaft assy is fitted, all I have to do now is epoxy the whole set up.
Mark have I measured the shaft angle correctly, using the keel as the flat line?


enjoyment is important.
RNinMunich
(Fleet Admiral!)





Forum Posts: 1497
22nd Dec 2017 23:34  
>> Permalink
mdlbt.com/36854

Hi Chris, Hi Mark,
"the flatter the better" is absolutely right to get more forward thrust and less forward pitch which pushes the bow down.
My concern is using the keel as the datum line!
Is the keel line parallel with the actual waterline when the boat is at rest? I doubt it, maybe - maybe not. I try to measure against the waterline in order to obtain the maximum forward thrust from a standing start.
Chris: I am also very interested to know where you got the digital angle device.
I have something similar but it's for building fitted cupboards and such and much too big for model stuff🤔
Merry Christmas all, Doug 😎


Young at heart - slightly older in other places 😉 cheers Doug
Grant me the Serenity to accept things I can't change,
the Courage to change things that I can, and
the Wisdom to know the difference!
RichardSReade
(Sub-Lieutenant)





Forum Posts: 45
23rd Dec 2017 08:03  
>> Permalink
mdlbt.com/36865

Doug, Richard hereit is me that has the digital angle, I got it from a company called Rutland's here in the uk, www.rutlands.co.uk/,
Thanks for the info about the water line, looks like I am going to have to use the bathroom bath again as I do not have the waterline marked as I have been experimenting with batteries and their position, the way I see it although I have arrived at a decision using a 56mm prop at the present angle, how do I decide the correct waterline at rest?


enjoyment is important.
ChrisF
(Sub-Lieutenant)





Forum Posts: 42
23rd Dec 2017 11:43  
>> Permalink
mdlbt.com/36870

Doug makes a good point about the prop shaft angle with regards to the waterline. Having said that I reckon once on the plane the keel/bottom of the hull will be fairly parallel to the surface of the water so using the keel as reference in this type of boat is fine.

Also if you start changing the angle you might have a larger hole in the hull which you have avoided so far!

In addition you might have problems with mounting the motor lower down.

Chris


Concentrating on the fine Fairey Marine boats
RichardSReade
(Sub-Lieutenant)





Forum Posts: 45
23rd Dec 2017 12:37  
>> Permalink
mdlbt.com/36871

ChrisF I have now floated the boat in the bath tub and measured the top edge of both the front and rear down to the water, back in the workshop I put some masking tape from the waterline mark from front to rear keeping the tape as straight as possible, it is not a million mile away from the Keel less than 2 degrees difference. so the prop will stay where it is. I have also now rubbed one side of the hull down and masked it to the water line and resprayed the top half white, the lower part of the hull will be resprayed black, the waterline line will be put on this. I will then repeat on the other side. I hope this will be correct.


enjoyment is important.
RNinMunich
(Fleet Admiral!)





Forum Posts: 1497
23rd Dec 2017 12:41  
>> Permalink
mdlbt.com/36872

Heartily agree on all points Chris👍
I am faced with the same decision with the restoration of my Sea Scout.
On the basis of 'if it ain't broke don't fix it' I decided to leave the shaft angle as Dad built it in the mid sixties to fit his Taycol Target.
I've now fitted a brushless and made a new shaft for the original tube, repainted hull and fitted out the 'engine room'. Pics show starting point and current state. Can't wait for the weather to warm up to try her out😉
I'm aiming for a trim at rest slightly nose up and water about 1/2 inch or so up the transom. Then trials to see if she comes easily on the plane and is stable. As usual a bit of trial and error, aka 'suck it and see' 😁
Happy Holidays and sailing all, cheers Doug 😎


Attached Files - Click To View Large


Young at heart - slightly older in other places 😉 cheers Doug
Grant me the Serenity to accept things I can't change,
the Courage to change things that I can, and
the Wisdom to know the difference!
rmwall107
(Lieutenant)





Forum Posts: 32
23rd Dec 2017 13:19  
>> Permalink
mdlbt.com/36873

Hello
I have had a simular problem with my build 'Richards Swordsman' and have had the same advice to reduce the angle of the shaft. unfortunetly i have already replaced the shaft! i am wondering if i can use a flexi shaft through the existing shaft and bend the shaft parallel to the keel as suggested. are there any problems with doing this?

ChrisF
(Sub-Lieutenant)





Forum Posts: 42
23rd Dec 2017 15:47  
>> Permalink
mdlbt.com/36879

I should try it as it is first Richard.

Prop shafts can be up to around 15 degrees, especially when they were installed for use with IC engines and they must have been alright then.

Chris


Concentrating on the fine Fairey Marine boats
RichardSReade
(Sub-Lieutenant)





Forum Posts: 45
23rd Dec 2017 16:05  
>> Permalink
mdlbt.com/36880

Chris if you were replying to my post and not rmwall107 who inadvertently hijacked my thread, no offence and I am happy about it, but it does lead to confusion as maybe rm might mean we have two Richards on the same post, anyway back to my reply, this is the last time I will be making any alterations to my Sea Commander, what will be will be now. I wish to get to grips with my Lloydsman tug


enjoyment is important.
Dave M
(Fleet Admiral!)





Forum Posts: 1527
23rd Dec 2017 16:23  
>> Permalink
mdlbt.com/36881

The Sea Commander and others from the 1960s all seem to lack any real waterline. Primarily they were designed to race round the sailing waters whilst runing a IC engine and were not normally static the water unlike today. We have several in our club and I have attached a few pics. The Tarpon was a similar model and the waterline is shown on the example. Two shots of my Sea Queen at rest and at low speed. The propshaft adjustment from the original design is minimal, really just lowering the angle to allow the motor to sit lower whilst allowing the prop to clear the hull.
On all my models I fit the shaft in a slot in the keel and make good with Car Body filler (Plastic Padding). This avoids the possibility of twisting or bending the shaft when fitting in a tight slot.
Merry Christmas and I hope Santa brings you all you desire.


Attached Files - Click To View Large


Live long and prosper

Dave
canabus
(Fleet Admiral!)





Forum Posts: 93
24th Dec 2017 08:14  
>> Permalink
mdlbt.com/36890

Hi
Replacing the drive shaft with a flex drive can be done, but, flex drives DO NOT LIKE REVERSE !!!!
They are only design for high speed boats.
Canabus

RNinMunich
(Fleet Admiral!)





Forum Posts: 1497
24th Dec 2017 09:06  
>> Permalink
mdlbt.com/36892

Right Canabus, AND-
they usually run in special tubes with Teflon bearings and lining tubes.
If you put one in your old tube without a liner it will probably rattle and bang like the 'big ends' are shot😡
Re tube bending: don't know how you propose to do it but I wouldn't attempt it, it's dangerous!
1) It may cause a kink instead of a smooth curve; thus increasing friction at that point.🤔
2) Most likely instead of bending the tube you will break the tube out of the keel causing considerable damage to the hull.🤔🤔
Up to you but I wouldn't risk it.
Good luck, Doug 😎


Young at heart - slightly older in other places 😉 cheers Doug
Grant me the Serenity to accept things I can't change,
the Courage to change things that I can, and
the Wisdom to know the difference!
jarvo
(Fleet Admiral!)





Forum Posts: 550
24th Dec 2017 10:01  
>> Permalink
mdlbt.com/36893

Hi Richard, mega warning, do not try to bend the prop tube in situ, it is thin walled and large diameter, a recipe for disastrous kinking. What Canbus and RN were referring to are racing drives, and they are replaced almost after every race.
Mark


Etherow Model Boat Club
RNinMunich
(Fleet Admiral!)





Forum Posts: 1497
24th Dec 2017 11:34  
>> Permalink
mdlbt.com/36895

Hi Richard, ta for the tip re angle gauge 👍
Just found it and am about to order. Lots of useful 'stuff' on their site 😉

Have a good Christmas, Cheers Doug 😎


Attached Files - Click To View Large


Young at heart - slightly older in other places 😉 cheers Doug
Grant me the Serenity to accept things I can't change,
the Courage to change things that I can, and
the Wisdom to know the difference!
RichardSReade
(Sub-Lieutenant)





Forum Posts: 45
24th Dec 2017 12:43  
>> Permalink
mdlbt.com/36897

Brilliant, I have been using them for years, you can sign up for their news letter with their daily deals and stuff.
A quick question to any sage, as I am doing a repaint of the hull, I thought I would fit a water pick up, which I have done, but where is the best place to fit the water outlet on a Sea Commander?
To all a Happy Christmas and a prosperous New Year


enjoyment is important.
Colin H.
(Fleet Admiral!)





Forum Posts: 287
24th Dec 2017 15:09  
>> Permalink
mdlbt.com/36903

My personal choice would be transom like an exhaust. I've done this on a few boats and can look quite realistic when sailing.


Fair winds and calm waters,
COLIN.
RNinMunich
(Fleet Admiral!)





Forum Posts: 1497
24th Dec 2017 15:24  
>> Permalink
mdlbt.com/36906

Exactly Colin 👍👍👍
That's where mine will be on my restored Sea Scout.
Wonder where it was on KGV and PoW?? 😉
Merry Christmas and Happy, and above all, Healthy New Year
Doug 😎


Young at heart - slightly older in other places 😉 cheers Doug
Grant me the Serenity to accept things I can't change,
the Courage to change things that I can, and
the Wisdom to know the difference!
jarvo
(Fleet Admiral!)





Forum Posts: 550
24th Dec 2017 18:33  
>> Permalink
mdlbt.com/36910

Hi Guys, for looks i agree the transom is the place, but, it is hidden by the wake, a safe place is to 1 side or the other, you can see the water coming out
Mark


Etherow Model Boat Club