Vintage Gentleman’s Cruiser

[CookieOldParticipant @cookieold]

Hi Bob , The new layout looks great , will you still be able to see both Able drives through the veiwing window ? . I dont know if you have got your prop shaft supports yet but if not Technobots do a nice range.

Best Regards Dave

[Bob Abell 2Participant @bobabell2]

Hello Dave

Just had a chap on the phone, asking the same question!……..What a coincidence

And the answer is no!………I can either move the motors 200 mm aft or fit a viewing window in the cabin wall with a hinged cover……Opening a side door is a novel feature

With all the gear in the front, the motors need to be further aft anyway

The caller has suggested gratings in the scuppers…….and a bilge pump…….Another nice idea

Thanks for calling in, Dave

Bob

[shipwrightParticipant @shipwright]

Hello Bob,

What is the length of your propshaft ? The reason for the question is that if they are as long as they look in the photo there might be a problem with vibration – overcomeable if there are bearings supporting the shafts in the middle. The Abell Drives are certainly have an impressive appearance.

Ian

[Paul TParticipant @pault84577]

Bob

What is Joyce putting in your Horlicks as this feels like deja vu 

The propshaft angle is 2.60deg.

The new motor layout might present you with some problems colliding with the floor of the rear cabin.

Paul

 

 

Edited By Paul T on 28/11/2014 12:00:18

[Bob Abell 2Participant @bobabell2]

Hello Ian

Pleased you like the ABELL Drives………They certainly are unusual and eye catching!

The propshafts are about 20" long, and will have extra bearings midway

The propshafts will be unusual, if we go ahead with my latest kinky idea……Wait and see!

Thanks for your comments

Bob

[Bob Abell 2Participant @bobabell2]

Hello Paul

Thanks for the angle, but I require the distance between the propshafts…..You might have said 160mm?

Can't see a problem with floor collision at the moment?……Give us a clue, please

Bob

[Paul TParticipant @pault84577]

Hi Bob

The distance between the shafts is 160000u (I can be just as pedantic)

The obstruction might occur when you position the motors in the space between F5 and F6 as the rear cabin intrudes into the space.

Paul

[Bob Abell 2Participant @bobabell2]

Hello Paul

My cabin hasn't got a floor above the motors

Early in the build that's how I imagined the engine room to be like……….Uncanny eh?

Thanks for the controversial dimension

Bob

[Paul TParticipant @pault84577]

I do like to be controversial but not with dimensions.

Where are you going to put the battery packs?

[Bob Abell 2Participant @bobabell2]

The batteries and all loose items will go in the bow section…..Out of sight

It will mean long wiring but I want the engine room to look like a engine room….If that's possabell?

Bob

[curlyParticipant @curly]

Hi Bob

If you do get shaft whip ,get in touch http://WWW.motionco .co.uk. They do pillow bearings, they worked for me on a long shaft,on one of my tugs. Hope this helps.

Regards Curly

[Bob Abell 2Participant @bobabell2]

Many thanks Curly

Motionco is a very handy supplier for engineering stuff…….I got the timing belt gear from them……Three day delivery too

Shop floor staff with cap in hand to Technical dept

As expected…….Having a problem with the propshaft route

The motor drives will have to move well forward of my Pie in the Sky intended position!

Obtaining the design angle of 2.6 degrees is a Bridge too far!

But wait!…….I have a novel idea!……..Groans in the wings

From the motors, at an angle that would cause Paul to faint in sheer horror, to a point in the rear scuppers, we could fit a Universal Joint!……Wow!…..Brill!…..Tell us more please

With a little bit of luck, the outgoing shaft could be horizontal!………Wow again……….Maybe

What does the team think?………We are warming to the idea, Capt

After Breakers, I'll look into it and report back………Where's me Wheatabix?

Capt Bob

Edited By Bob Abell on 29/11/2014 07:02:58

[shipwrightParticipant @shipwright]

Bob,

Although very good for minor shaft misalignment, universal couplings tend to be noisy and lower drive efficiency if the misalignment is significant. If universal coupling is the only way forward then use 2 universal joints in tandem. What is the likely rpm of your drive on full ahead ? In my model destroyer I have used universal joints in tandem without difficulty but the max rpm is only 1100. The problem with universal joints is that there are not perfectly balanced and that becomes noticeable at higher rpm (can results in noisy resonances).

With your mechanical arrangement, you have an additional item in the dynamic system namely the resilience of the toothed belt (think of the total drive system in terms of rotating masses, frictional loads and springs (toothed belt and shaft torsional elasticity). For example if the parameters of the motors are not perfectly matched there might be a tendency for the shaft to speed up and slow down (slightly) leading to a resonance – the frictional losses should help to damp out this oscillatory behaviour.

Ian

[Paul TParticipant @pault84577]

Bob

As Ian has quite rightly pointed out universal joints are noisy and inefficient.

The solution to your problem is relatively simply and already at your fingertips.

But first what are the current shaft angles for your 'pie in the sky' motor positions.

Paul

[Bob Abell 2Participant @bobabell2]

Hello Ian

Thank you for your constructive advice……….I`ve looked at UV`s in the Motionco website and the cheapish ones have a max speed of 1000 rpm and we are hoping to run at 8000 rpm

So UV`s are out of the equation now

Have cut out the hull for a trial setup and it appears that we don`t have a problem……Might even get down to 3 degrees

The only snag is that the propshafts will be 30" long!

Photo to follow shortly

Bob

[Bob Abell 2Participant @bobabell2]

Hello Paul

The shaft angle at the moment is about 5 degrees

Before I assault the hull, what's the solution already at my finger tips?

Bob

[ashley needhamParticipant @ashleyneedham69188]

I am sure that the offshore racing boys must have suitable flexible joints able to withstand a few thou RPM?? You are only looking at a few degrees off.

Ashley

[Paul TParticipant @pault84577]

Bob

Its really quite easy to achieve the prop shaft design angle as its just a matter of adjusting the angle of the final drive belt on your motor packs.

There will be a little adjustment to the motor pack mounts but everything is straightforward.

To solve the whipping problem just fit bearing points on each frame (just like a line shaft)

Paul

Yet again the cool headed and unflappable thinking of the design office has rescued the workshop from disaster. This just goes to show what happens when Horlicks is mixed with Sanatogen. lol

 

Edited By Paul T on 29/11/2014 11:47:50

[Bob Abell 2Participant @bobabell2]

Thank you Paul

I did notice this morning that the motor drives need not be on the hull centreline……So no marks for Paul for that suggestion

Also noticed that for our slow moving boat, the 2,7 degree angle ain't that essential either…..So no points for mon ami

The slender line propshafts have mid bearings anyway……So you've scored nil poise!

I'm only pulling your leg……lol

I am quite relieved that the propshaft route has been sorted out

I'll try and get the angle down a bit more

Bob

[Dave MilbournParticipant @davemilbourn48782]

I'll try and get the angle down a bit more

Why? As you say, for a slow-moving boat it's not that essential. IMHO it's not even that essential for a fast-moving boat either (See Huntsman, Perkasa etc etc). And for two degrees – when it's already just about dead level???

It's maybe a magnificent obsession – but it's still an obsession. Why make work for yourself? The difference in performance would be infinitesimal i.e. it would be very difficult to measure and you could easily make it up with an extra coat of polish. Trust me – I've cobbled up a few of these silly things, too.

DM

[Bob Abell 2Participant @bobabell2]

I agree with you, Dave, but Paul has a bee in his bonnet about prop angles

If I can get the angle down……So much the better

Bob

[Colin BishopModerator @colinbishop34627]

Z Drives Bob, Z Drives….

Colin

[Bob Abell 2Participant @bobabell2]

Sorry Colin

What are Z drives?

Bob

[Dave MilbournParticipant @davemilbourn48782]

I agree with you, Dave, but Paul has a bee in his bonnet about prop angles

Then just tell him lies! It needn't be a big one 'cos it's only a tiny wee angle. We'll keep it between ourselves, eh?

Here's a Z-drive **LINK** Two of these would cost nearly as much as Andrew Mitchell's legal team………………..or David Mellor's taxi fare.

Dave M

[Bob Abell 2Participant @bobabell2]

Thanks Dave

Tell him lies!…….Couldn`t do that……..He`d get his super precision clinometer out and catch me at it!

As for the Z drives……Too late was the cry!

Bob

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