nb Beech

[gazza]

Ahh, my experience has been different, everyone has recommended these:

That's an ace looking bit of kit.

For me a slight drop in efficiency would be more than compensated by the absence of a stern gland.

I wonder what it's maintenance requirements and its shaft sealing arrangements are.

Not having as big a sinking risk in the back of the boat is a huge plus!

 

My approach would be to get the details of that drive unit and speak to someone like this http://www.aircarecompressors.co.uk/sales/11-omc about system requirements design and efficiency (I use OMC and would prefer someone like them to talk tech)

 

You could go diesel electric if hydraulics still give you the Willies.....

[Guest]

A bit tangental to poor Beech - I've investigated the diesel electric scene quite thoroughly, IMHO it's worth waiting five years and then they'll be a variety of options on the market; our sector of the marine industry has been pretty much overlooked at the moment as there's no real incentive for users to go electric., those who want to use the Beta system.

 

There seems to be very little mix and match flexibility for the systems at market at the moment; Steyr's alternator and control system for example is superb, but can only be used with a Steyr engine etc.

 

I'd originally considered the Bladon genset and an Oceanvolt sail drive, but neither are ready, even for a testing phase.

 

The stern gland omission is a huge plus - a significant part of our build budget will go on Jotun epoxy paints for longevity, but always best to keep the wet out all together in the first place. Hydraulic may also some offer advantages with selectable alternators too.

[Tony Dunkley]

Ahh, my experience has been different, everyone has recommended these:

 

Having a deadwood or sternpost which will accommodate that clumsy piece of equipment just ahead of the propeller would make the efficiency losses from the hydraulic drive pale into insignificance.

[Guest]

Could you support that with some figures Tony?

 

Only I reckon I can save 10% resistance by fining the hell out of the hull - but you reckon more than 20% just from the stern post? I'm curious...

 

I assume from the taper of the aft swim that this is a generic clone craft, but you can see the installation at least. For a finer swim you order one with a longer tube. Can't see much difference over a standard installation myself...

Edited January 16, 2016 by dpaws

[gazza]

Dpaws,

 

I'll have a stab at answering it for you.

 

Tony is trying to sound as though he knows what he is on about.

As ever a picture says a thousand words and should hopefully clear up Tony's misunderstanding of how that tasty hydraulic unit is fitted.

 

I thought it was obvious how it would be installed.

 

So to sum up, it will make the square roof of naff all difference to performance and efficiency.

 

It will stop you having to grease and tighten a traditional type stern gland, it also avoids the dubious deep sea type installations.

 

Have you any links to a manufacturer for said drive?

[Guest]

You could start here, never worked with them though I do recognise their name from this forum I'm sure... http://www.arsangliandiesels.co.uk/propulsion.htm

 

http://bsphydraulics.co.uk/BSP/PDFs/M_GB%20net%202014.pdf

 

A hydraulic drive will give you the trolling facility for locks without having to revert to an oversized 260 sized PRM gearbox, it should also allow you to chose a drive ratio more suited to your specific engine and hull, so you can fine tune - but to what extent and how fine those ratio steps would be I have no idea... yet... but I'm curious.

 

I'd be curious too about battery driven electric hydraulic motors being able to feed boost power back into the prop. I'll ask around and revert.

Edited January 17, 2016 by dpaws

[gazza]

Ta!

 

Will take a better look at that site when I'm at work.

 

I've worked in Wakey, apropos nothing, the water up there makes terrible tea and coffee, how the natives live with it I don't know

[Tony Dunkley]

Could you support that with some figures Tony?

 

Only I reckon I can save 10% resistance by fining the hell out of the hull - but you reckon more than 20% just from the stern post? I'm curious...

 

I assume from the taper of the aft swim that this is a generic clone craft, but you can see the installation at least. For a finer swim you order one with a longer tube. Can't see much difference over a standard installation myself...

 

You have completely misunderstood the 'efficiency losses' I was referring to.

I mentioned the hull structure ~"just ahead of the propeller"~ because it's the interference with the inflow of water to the propeller, that will reduce the operating efficiency of it. The effect on hull efficiency at the sort of speeds you will be achieving would be negligible.

The photo of that combined motor/thrust bearing/tailshaft/sterntube and seal unit installed in a typical modern canalboat illustrates the point very well. That squared off flat sternpost will make even more of a mess of the inflow to the propeller, which is already converging quite messily behind that much too widely angled side plating.

 

In addition to these considerations, you should also give some thought to the disadvantages that will come from having the tailshaft seal and thrust bearings carried externally and underwater in a housing which will be warmed up by the hydraulic motor and, in the same way as permanently immersed outdrives do, will draw in water as it cools down after every period of use.

Unlike a conventional tailshaft and stuffing box, the external seals will be very vulnerable to damage and wear from such as fishing line and/or gritty water, and the boat will have to be slipped or docked for attention to the tailshaft seal in the event of leakage or failure, . . something which may well only manifest itself through failure of the [roller or ball] thrust bearings due to water and dirt ingress.

You would be far better off forgetting about both your groundless fears of conventional sterngear and this unsuitable, high maintenance and potentially unreliable piece of equipment.

Edited January 17, 2016 by Tony Dunkley

[Guest]

Thanks Tony - but I'm still waiting for your numbers that push hydraulic drive losses into insignificance. I suspect your fears about the drive seal may have been considered during the design process, but if you'd care to share the failure rate statistics I'd be most grateful...

 

Otherwise we have a forum of misguided opinions that only serves to mislead others. I prefer to consider facts during my design process, especially when they have evidence that support them.

 

I completely disagree about the structure ahead of the prop - it only disturbs the efficiency if is detrimental to the flow, in fact, if you look at many vessels they deliberately add things in that zone to stabilise the and control it better.

 

Whilst the example I showed had a blunt stern post, I conceded that when I posted, rest assured I won't be using the same aft profile, as I'm sure you've gathered from the thread. In fact, the swim angle in the foto is probably within 10° of the Josher design, it's quite a course angle. To use a more acute closing angle then you simply lengthen the tube, the stern tube penetrates the trailing edge and protrudes beyond it, it doesn't determine the aft profile at all. The pic shows a slight extended drive tube, I don't have another to hand.

 

Leading or trailing tubes in profile aren't going to disturb much at all, think pitot tubes. Squared off rear profiles are awful, but I wouldn't square off a sternpost, even a gentle taper will start reducing the resistance down to around 15%, about that of the Schilling rudder profile whose trailing edge is typically squared.

 

In terms of reliability I'm not sure on the moving component count that we're so far behind with full hydraulics that with that of a conventional system, especially one that involves the hydraulic gearbox mentioned before that offers the trolling facility.

 

I gather that you don't like hydraulics, many don't. It's an option that's on the table. When considered as a system overall it maybe beneficial to follow that route, it will be a calculated and considered decision that's taken when all the info is to hand.

[Tony Dunkley]

Thanks Tony - but I'm still waiting for your numbers that push hydraulic drive losses into insignificance. I suspect your fears about the drive seal may have been considered during the design process, but if you'd care to share the failure rate statistics I'd be most grateful...

 

Otherwise we have a forum of misguided opinions that only serves to mislead others. I prefer to consider facts during my design process, especially when they have evidence that support them.

 

I completely disagree about the structure ahead of the prop - it only disturbs the efficiency if is detrimental to the flow, in fact, if you look at many vessels they deliberately add things in that zone to stabilise the and control it better.

 

Whilst the example I showed had a blunt stern post, I conceded that when I posted, rest assured I won't be using the same aft profile, as I'm sure you've gathered from the thread. In fact, the swim angle in the foto is probably within 10° of the Josher design, it's quite a course angle. To use a more acute closing angle then you simply lengthen the tube, the stern tube penetrates the trailing edge and protrudes beyond it, it doesn't determine the aft profile at all. The pic shows a slight extended drive tube, I don't have another to hand.

 

Leading or trailing tubes in profile aren't going to disturb much at all, think pitot tubes. Squared off rear profiles are awful, but I wouldn't square off a sternpost, even a gentle taper will start reducing the resistance down to around 15%, about that of the Schilling rudder profile whose trailing edge is typically squared.

 

In terms of reliability I'm not sure on the moving component count that we're so far behind with full hydraulics that with that of a conventional system, especially one that involves the hydraulic gearbox mentioned before that offers the trolling facility.

 

I gather that you don't like hydraulics, many don't. It's an option that's on the table. When considered as a system overall it maybe beneficial to follow that route, it will be a calculated and considered decision that's taken when all the info is to hand.

 

I don't have the time today to deal with all the issues you're raising here, but with regard to the problems with the type and location of the seals in that drive unit, I can tell you that what I've said isn't based on 'fears', or any abstract opinions, but from first hand experience of failures and damage to similar set-ups on drives ranging from units such as Schottel and Harbourmaster to Enfield Z-drives on a variety of inland waterway vessels from commercial tugs to pleasure craft.

With units like the Schottel in use on tugs, the vulnerability to damage and increased maintenance and repair is accepted as an unavoidable evil in return for which you get much improved manoeuvreability, but in using that seal system on a fixed and otherwise conventional tailshaft drive, but with external thrust bearings, then you're ending up with the potential problems associated with drives such as Schottel and none of the advantages.

You also seem to be harbouring some misconceptions about PRM gearboxes. They are not 'hydraulic' boxes, and I'm totally mystified by this 'trolling facility' that you're talking about. PRM's are mechanical, layshaft type, boxes with two sets of friction clutches which are engaged by means of oil pressure in integral hydraulic cylinders in each clutch assembly.

The reliability question arises from the high probability of failure of the external thrust bearings following seal failure, and not the reliabilty of the power transmission components, whether hydraulic or mechanical.

 

I fully understand what you're doing, and why you're doing it, but it is apparent that your knowledge about and on the design and propulsion of inland waterway vessels is limited to what you've gleaned from published material of varying worth and relevance from many different sources, and not from practical experience.

I have no wish to belittle your efforts, or what you're attempting, but believe me, you are showing signs of heading down the same blind alleys, that I've seen others go down before you, and I don't want to see you disappointed with the end result.

Edited January 17, 2016 by Tony Dunkley

[pete harrison]

Is 36hp less 20% enough power? depends on the hull resistance... welcome to my world

I do not really want to get too involved with this thread as I do not believe the 'the wheel' needs re-inventing, and I have seen numerous improved design narrow boats over the past 45 years that only result in something to mock (but not by me because I am only interested in 'historic' design and I do not really notice modern boats).

 

I have found an engine horse power to have little relevance in a canal boat, but torque to have great relevance. My view, and not proven by any science, is that a slow revving traditional type engine of about 20hp is more than sufficient providing that it has loads of torque and can turn a large propeller - and that a large propeller turning relatively slowly is much better than a small propeller turning fast

[Derek R.]

We started off looking at BEECH as a basis for copying the dimensions for a new build. Whilst the divergence into hull specs and drives is an interesting and complex subject, it should be noted that within the History & Heritage section most folk are apt to accept what has worked for the past ninety odd years has done so because it works. Whilst new builds and their designers might choose to diversify - and good luck to them - the cut, with all its glorious contents other than water and the historic boats thereupon, has been managing without fixing something that ain't broke for quite a long time. These are not misguided opinions, nor are they from a group of Luddites, but from past experience of what works well enough. Seeking some form of perfection is in itself a dead end. One might design and build something different and in the eyes of the designer/builder gloriously better than what went before, but it's the same old shopping trolleys, tarp and tights that will be wrapped around the prop. Plenty of boats as are will exceed the 4mph speed limit on the cut with ease - slow revving large diameter props, stern glands and all, and that do not sound like van engines but something more associated with ex-working boats.

 

I would not be surprised that by the time this hull has been designed, built, powered, fitted out etc, the amount of money spent will cover the cost of BEECH, and a whole lot of docking to repair whatever timbers that may be needed for the next decade or more - and still not be anything like BEECH is.

[Tony Dunkley]

I do not really want to get too involved with this thread as I do not believe the 'the wheel' needs re-inventing, and I have seen numerous improved design narrow boats over the past 45 years that only result in something to mock (but not by me because I am only interested in 'historic' design and I do not really notice modern boats).

 

I have found an engine horse power to have little relevance in a canal boat, but torque to have great relevance. My view, and not proven by any science, is that a slow revving traditional type engine of about 20hp is more than sufficient providing that it has loads of torque and can turn a large propeller - and that a large propeller turning relatively slowly is much better than a small propeller turning fast .

 

And relatively slowly being a maximum of no more than 600 rpm, with 500 rpm the more usual.

The modern preference for small diameter and high propeller speeds, in the region of 1500 rpm, is certainly one major factor in the poor performance that has come to be the accepted norm by the owners of modern so-called narrowboats. The pitiful 5 to 6 knots that the swiftest of most modern boats can achieve with up to around 40 or 50 hp in deep water on a river isn't much better than what a pair of loaded Grand Unions could manage in deep water with an 18 hp National, or later on with a 20 hp Petter turning the same blade with a bit more lift knocked on to it.

Edited January 17, 2016 by Tony Dunkley

[Guest]

I completely agree with both of you, and your kind patience is appreciated. I still haven't ruled out the possibility of Beech, I can afford the upkeep, it's only she's come a little early for us, we need more practicality for us and after something that little 'un can use for Uni digs. By that time I'm very much hoping to be behind a smoking Samofa singing a happy tune, weeping stern glands 'n all.. unless she decides that a Tyler Wilson Sheffield Keel is for her... and then we need to talk!

 

Am I right in thinking that you can't really fit out an interior in the hold on a wooden narrowboat because you'd need to destroy it every time the planking needs repair work?

 

If it's torque or hp, my sense is that it's energy out of the engine - against all of the losses, whatever we call them. I'll know once we're flat out on the Trent, but an additional power boost from the battery could be very useful indeed. I can size the prop for the total output and benefit from lower revs with a larger diameter during day to day cruising.

 

The Bukh 36 has a marine friendly torque curve - we're still nowhere near the older engines, but it's a little better than the tractor stuff - I'm quietly confident that 36 Bukh horses will be sufficient, we'll just have to see what she can swing, I've the correct spacing for up to a 21", I'd need a bigger engine room compartment for anything more powerful. I value Bukh turn key reliability as our guests will be taking the boat out, and not all of them would get the pleasures of blow lamps and hand starting. From the forum elsewhere:

 

BMC 1.8: 36hp @ 3000 rpm = 63 ft lbs

Petter PH2W: 16.5hp @ 2000 rpm = 43 ft lbs
Lister FR2: 18hp @ 1800 rpm = 53 ft lbs
RN DM2: 18hp @ 1000 rpm = 95 ft lbs

 

The hydraulic PRM range starts with this model, with optional trolling valve: http://www.prm-newage.com/p13-prm260

 

 

PRM260

Full hydraulic operation, lightweight, compact & rugged.

A trolling valve can be fitted. This is electronically operated which allows variable speed of the propeller to zero whilst allowing a maximum engine speed of up to 1200 rpm.

 

The reason I value this is for locking single handed, gentle rpm fwd will help to keep the stern away from the cill.

Edited January 17, 2016 by dpaws

[Derek R.]

On deep Yorkshire waters, Petter PD2 rated at 20hp @1500rpm, with a 3:1 reduction swinging a 24" dia. x 27" pitch blade. (It ought to have been a 27" x 23", but insufficient room under the counter). The two vessels accompanying us were powered by Bolinder Munktel 1053's around 36hp with less reduction, and would keep up - but no faster. Draught 2' 3" static, pushing on 2' 6" and some.

 

Apologies for my incorrect steering position, but my back trouble was giving me stick.

 

Stern gland leakage around two pints for 8hrs cruising caught in a purpose made container (an old potty). A twist on the greaser stopped it for overnight.

 

Edited January 17, 2016 by Derek R.

[Guest]

I'm quire liking that pose, just missing the cuppa... nice fine bow, cutting through the wave - thanks for sharing

 

But that sounds like a stern gland I'd want to design out! Is that typical or is she due for a little attention? Could you direct any spare transmission heat that way so it evaporates out, or does that accelerate corrosion unaccptably? Suppose you'd have to black it when you do the hull...

 

The Mrs watched a Youtube clip with a chap mopping out the bilge with nappies (most impressive) but decided then and there that she didn't want that mess on her (!) boat. I know too that guests wouldn't be as fastidious mopping out and with us living many miles away the water would sit and the corrosion would be inevitable.

 

If you look through the excellent Rugby Boats video tours (who doesn't? thanks Dominique) you'll note the number of corroded stern tube areas when the rest of the shell looks in fine fettle.

[mark99]

Our stern gland has never leaked more than 5 drips in years.

[Guest]

I assume the excessive weeping is usually down to precise shaft alignment, is it pot luck on the day or are there some wizards with laser are sites that perform micron perfect installations? Does the hull's expansion affect that alignment from winter to summer?

[pete harrison]

The Mrs watched a Youtube clip with a chap mopping out the bilge with nappies (most impressive) but decided then and there that she didn't want that mess on her (!) boat. I know too that guests wouldn't be as fastidious mopping out and with us living many miles away the water would sit and the corrosion would be inevitable.

I worked on the boats for several years, and have been involved with numerous 'historic' boats since and I have never mopped out the bilges - let alone with nappies. I did however have a bilge pump that removed most of the water in the bilge, which was a combination of stern gland drips and condensation.

 

It seems to me that many boat owners nowadays would be more suited to a cottage, or at least a boat on the bank where they would not need to worry about water (either inside or outside the boat), continuous cruisers, other boats moving past them, the inadequacies of the operating Authorities e.t.c.

[Guest]

It seems to me that many boat owners nowadays would be more suited to a cottage, or at least a boat on the bank where they would not need to worry about water (either inside or outside the boat), continuous cruisers, other boats moving past them, the inadequacies of the operating Authorities e.t.c.

 

I do see where you're coming from, I'm sure we'll become more boat minded as our miles clock up, but also I don't feel the need to abandon comforts - you can extrapolate the argument further to not having microwaves etc. I though of "boats on the bank" for a low cost housing project, dig the hole and back-fill with pea gravel...

 

I'd rather have the cottage with the mooring at the bottom of the terraced garden, it's already on her list of things to buy haha

[pete harrison]

BMC 1.8: 36hp @ 3000 rpm = 63 ft lbs

Petter PH2W: 16.5hp @ 2000 rpm = 43 ft lbs

Lister FR2: 18hp @ 1800 rpm = 53 ft lbs

RN DM2: 18hp @ 1000 rpm = 95 ft lbs

I have experience of all of these engines and would consider the top three engines to be low powered and suited to a smaller propeller, but the Russell Newbery DM2 to be well suited to a large propeller - as reflected by it having much higher torque. Having said that the Lister FR2 was fitted into a few carrying narrow boats back in the 1950's and early 1960's, although I would say was best as a single motor without a butty.

 

All of these engines are available with electric starts, and there are very few engines that require a blow lamp.

 

If I were choosing a money no object engine it would be Russell Newbery DM2 if water cooled and a Lister 'H' series if air cooled, and my real preference is the latter. Some boat owners would complain about the noise / vibrations of these engines but these are of no interest to me

I do see where you're coming from, I'm sure we'll become more boat minded as our miles clock up, but also I don't feel the need to abandon comforts - you can extrapolate the argument further to not having microwaves etc.

I do not think I have ever been on a canal boat with a microwave, and I have rarely been uncomfortable - especially during the six years I lived in a back cabin (boatmans cabin in modern parlance)

[Derek R.]

(snip)

 

But that sounds like a stern gland I'd want to design out! Is that typical or is she due for a little attention? Could you direct any spare transmission heat that way so it evaporates out, or does that accelerate corrosion unaccptably? Suppose you'd have to black it when you do the hull...

(snip)

 

No attention needed. In fact, I guessed at 2 pints, probably less than a pint - a lot less, memory from 27 odd years ago! A tweak of the stuffing gland would stop it. Transmission heat? What transmission heat?

 

Beneath the stern tube on TYCHO

 

 

A few drips in a bowl are never a problem. Liquid cooling . . .

[WotEver]

Ooh look - rivets!

[Athy]

Yes, it's unusual for a builder to stick them on the inside of a hull as well as on the outside.

[WotEver]

They probably had a few spares and while the glue is handy why not?