nb Beech

[Guest]

I mentioned before the three plans at my disposal. I measured each across the bottom planking/baseplate for the distance behind the tip of the bow post to an external width of 140cm, this is to fit a 120cm wide "double" mattress plus 10cm either side for plate, insulation and panelling.

 

This point occurred 355cm / 140" aft on the Josher, 245cm / 96" aft on the Northwick and 228cm / 90" on the Woolwich - that's over 4ft between the Josher and the Woolwich, more than I expected.

 

While I was measuring, from the tip of the bow post until the bottom planking/baseplate is at full width is 620cm / 244" (Josher), 490cm / 193" (Northwich) & 430cm 169" (Woolwich)

 

I sensing that my anorak has a hood... maybe waist ties... with those hard plastic toggles, that aren't really chewable... probably in a primary colour... What else should I be studying obsessively in order to qualify for the matching wellies?

Edited January 16, 2016 by dpaws

[Derek R.]

I understood 4ft, other than that, I'd stop trying so hard.

 

Fine lines = less internal space. It's not rocket science.

[gazza]

Are those drawings all drawn at the same scale?

 

Ps, if you're using metric use mm as your unit, cm are for school kids and curtain makers

[Guest]

Are those drawings all drawn at the same scale?

 

Ps, if you're using metric use mm as your unit, cm are for school kids and curtain makers

 

You may well be right Gazza, but here in Italy where they use only metric everything is in cm - strange eh?

 

Yes, they are all 1:24 scale, I have a special ruler that measures in scale with marks in metres - assuming the drawings are correct obviously, but I've no reason to doubt them, at least not to the nearest cm.

[Pluto]

This is what you need for a boat that swims well, you will just need to scale it down. These lines were drawn by Jack Hodson, the owner of Whitebirk Dockyard, in the 1950s, and represent a wooden L&LC motor boat.

[Athy]

Ps, if you're using metric use mm as your unit, cm are for school kids and curtain makers

They are much harder for British people to understand. Centimetres can be easily related to inches, as two-and-a-half of them make an inch. Confronted with the measurements of, for example, a car expressed in millimetres - it runs into thousands - I tend to glaze over, and I'm sure I'm not the only one.

Edited January 16, 2016 by Athy

[gazza]

 

You may well be right Gazza, but here in Italy where they use only metric everything is in cm - strange eh?

 

Yes, they are all 1:24 scale, I have a special ruler that measures in scale with marks in metres - assuming the drawings are correct obviously, but I've no reason to doubt them, at least not to the nearest cm.

I was being mischievous

Most things sold in the UK tend to be listed in CM too.

 

Having spent all my working life reading, creating and working from drawings CM are anathema!

We were also taught to measure in thousands of an inch but thankfully this has largely become obsolete, we do get the odd drawing from the states but a quick go with the Zeus book or Google puts it back to metric - as used by the rest of the world

 

Perhaps Athy has it, shifting the decimal is too hard for the average Joe to grasp.

 

Glad to hear you are geared up correctly on your quest for your perfect boat

Edited January 16, 2016 by gazza

[Athy]

 

Perhaps Athy has it, shifting the decimal is too hard for the average Joe to grasp.

 

 

Rather, they're hard to visualise. If someone says that their boat is 45 feet long, I can easily imagine how long that looks. If they tell me that it's 13,500 millimetres long, I can't. Could you?

Edited January 16, 2016 by Athy

[gazza]

Rather, they're hard to visualise. If someone says that their boat is 45 feet long, I can easily imagine how long that looks. If they tell me that it's 135,000 millimetres long, I can't. Could you?

Yes, move the decimal to the left and it becomes 1 and 1/3 ish swimming pools wide (45' is 13716mm BTW - you can tell you taught languages )

Edited January 16, 2016 by gazza

[Athy]

Yes, move the decimal to the left and it becomes 1 and 1/3 ish swimming pools wide (45' is 13716mm BTW - you can tell you taught languages )

Original post duly corrected, thank you for pointing that out.

[keif's mate]

Back in the mists of time when I used to witter on to trainee Sparkies in Science classes, the question of measurement and units used to come up. The electrical trade was one of the first to metricate. As with any Engineering trade, metres and millimetres are used. The centimetre is a non preferred unt. Even kitchen cabinents are measured in millimetres not centimetres.

 

In the mid 80's, a fiirm of builders we used to contract to told all their Apprentices to "Forget that metric rubbish you were taught at school, we work in feet and inches" They nearest they got as far as metrification was "Brian, go and get me a 3 metre length of 4x2!"

 

The problem comes with visualisation. Probably not so much of a concern to a modern school leaver who doesn't know any better. However for old dinosaurs I used to use an example of the old London bus (probably a Routemaster!). Said bus weighed about 10 tons. Mild steel had a tensile strength of about 30 tons per square inch. So a mild steel bar with a cross sectional area of 1in² could lift 3 buses.

 

Trawling through the web gives a tensile strength for EN1A mild steel as 400MPa. What the 'ell are they! Converts to 58015 lbf/in² or about 25.9 tons. Seems like American mild steel SAE 12L14 is tougher, (it would be!!) at 540 Mpa, 78,300 lbf/in² or 34.95 tons!

 

1 Pascal = 1 Newton/metre² So that would be an apple on a square metre (Coxes Orange Pippin, Granny Smiths, Red Jonaprince, Cooker or ordinary?) Hardly a practical unit! No wonder kilopascals and Megapascals have to be used.

 

Ho hum, I suppose Imperial measurements will be all but forgotten in 50 years. But that doesn't account for the Americans whose idea of metrication is to take a drawing and convert inches to millimetres. So the measurement will be 25.4 mm!

[gazza]

Back in the mists of time when I used to witter on to trainee Sparkies in Science classes, the question of measurement and units used to come up. The electrical trade was one of the first to metricate. As with any Engineering trade, metres and millimetres are used. The centimetre is a non preferred unt. Even kitchen cabinents are measured in millimetres not centimetres.

 

In the mid 80's, a fiirm of builders we used to contract to told all their Apprentices to "Forget that metric rubbish you were taught at school, we work in feet and inches" They nearest they got as far as metrification was "Brian, go and get me a 3 metre length of 4x2!"

 

The problem comes with visualisation. Probably not so much of a concern to a modern school leaver who doesn't know any better. However for old dinosaurs I used to use an example of the old London bus (probably a Routemaster!). Said bus weighed about 10 tons. Mild steel had a tensile strength of about 30 tons per square inch. So a mild steel bar with a cross sectional area of 1in² could lift 3 buses.

 

Trawling through the web gives a tensile strength for EN1A mild steel as 400MPa. What the 'ell are they! Converts to 58015 lbf/in² or about 25.9 tons. Seems like American mild steel SAE 12L14 is tougher, (it would be!!) at 540 Mpa, 78,300 lbf/in² or 34.95 tons!

 

1 Pascal = 1 Newton/metre² So that would be an apple on a square metre (Coxes Orange Pippin, Granny Smiths, Red Jonaprince, Cooker or ordinary?) Hardly a practical unit! No wonder kilopascals and Megapascals have to be used.

 

Ho hum, I suppose Imperial measurements will be all but forgotten in 50 years. But that doesn't account for the Americans whose idea of metrication is to take a drawing and convert inches to millimetres. So the measurement will be 25.4 mm!

That deserves a greenie, amazing to think after all these years of SI units there is still plenty of discussion and confusion to be had.

 

And that's before you start on things like do you want 1000 meters or do you want to travel 1000 metres?

[keif's mate]

Well, well, a greenie, thank you Sir.

 

"And that's before you start on things like do you want 1000 meters or do you want to travel 1000 metres?"

 

Homonyms, no, not rude or illegal, but who would expect an engineer to know that!!!

[Guest]

Two pre nb Beech measurement guesstimates, both hulls fit a common interior layout - same length, gunwale height etc.

 

Limiting factors are a 120cm mattress under the foredeck and a Bukh 36 engine aft. Not so easy to show in 3D, it takes some getting used to, but I think the differences are apparent.

 

The XR&D slipper type stern has been refined with a flared pod that accommodate the engine, and lengthened out to 17', similar to the Town class boats.

 

The stern of the second closer resembles an Edwardian launch.

 

The finer of the two bows is the same height as a Josher, the buff is Town class height, 6" lower...

 

(Pls excuse my CAD, it's very WIP and I'm a newbie to 3D - it drives you nuts on a 13" laptop with only a touchpad!)

Edited January 16, 2016 by dpaws

[FadeToScarlet]

Why have a flared part for the engine, why not a hydraulic or electric motor, so the engine can be elsewhere and accessible from both sides?

[gazza]

Why have a flared part for the engine, why not a hydraulic or electric motor, so the engine can be elsewhere and accessible from both sides?

Indeed.

 

A hydraulic system is an excellent choice, sadly they have an undeservedly poor reputation in the ditch crawling world.

No such problems on the Broads hire fleet who place the engine well out the way to maximise living space.

 

Theres a fair few machines in industrial and agricultural applications that use reliable hydraulic systems too.....

[Guest]

A 20% power loss, (only 3% gearbox/shaft). Power train more efficient at fixed rpm but don't want the sensation of being sat on the motorway when we're on board.

 

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

 

(For diesel electric gensets consider the Polargen 20kW for low tech, the Steyr MO32 APU 20kW for mid tech or the Bladon MTG 12KW for high tech)

 

Regarding access it's actually not too bad within the pod, full overhead and rear access, the top 60% accessible from the front and around the sides the minimum service distances are maintained.

Edited January 16, 2016 by dpaws

[gazza]

A 20% power loss, (only 3% gearbox/shaft). Power train more efficient at fixed rpm but don't want the sensation of being sat on the motorway when we're on board.

 

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

1hp was adequate once upon a time

 

Plenty of broads boats did (and do) sterling service with a BMC 1500 or an old Perky 4107 and some tides to contend with.

 

If you are worried go for 45+ bhp. You will likely use more power driving gert big alternators than shoving the boat up a ditch anyway!

 

Added, all boats should have a wet exhaust, except for stuff that runs out of puff at 600 odd RPM.

whizzy high speed diesels with dry exhausts sound like vans anyway.

Edited January 16, 2016 by gazza

[Bee]

36HP less 20%, Just to lift the lid on a huge can of worms and byzantine maths, if it will spin a 17"os 18" propeller in a blur then its powerful enough.

[Guest]

Yes Bee, It is a huge can of worms! I like the idea of hydraulics also because I can remove the stern gland from the system, but it incurs more complexity and a pressurised system that will need another level of bureaucracy and Certification. I've much to lose and little to gain, I can achieve a trolling valve with a swap over to a PMC260 gearbox with similar gear ratios (and a kinder propshaft offset)

 

I flatly refuse to add more hp because that's what Americans do to resolve problems they don't understand, like with their muscle cars...

 

I reckon with the finer of the two sterns and the original high ratio gearbox we'd swing a 20" Axiom, not sure what 20% less than a 20" prop is, but 17"/18" probably isn't far off....

 

Because the interior is designed with a conventional engine layout in mind there's not really many gains to be had from moving the engine, the interior is happy designed around it (or over it, to be more precise)

 

The Bukh I understand is very similar to the BMC 1.5, albeit refined to minimise vibrations in a marine environment. I'm not much of an engine man beyond 2 cyl Guzzis and Continental A65s, at the moment I don't miss the grease.

Edited January 16, 2016 by dpaws

[gazza]

I'm not sure the losses will be anything like 20% btw, would need to see the pump and motor specs to make an informed decision on that.

 

The yanks DO have it right, there's no substitute for cubes - and 8's are great.

 

I'm not sure what bureaucracy and certification you are referring to. All you need is a well designed and installed system. There's no issues with pipework. Hoses last years and are dirt cheap to replace anyway.

Rigid pipework mounted correctly will never need touching.

Pumps and motors will serve many many thousands of hours with not much more than an oil and filter change once in a while.

 

Honestly, you are making more of an issue out of it than needs be.

 

I will take a picture of a hydraulic set up we have at work, its a shear mixer that blends two ton of resin at speeds that would punt a narrow boat up a canal rather rapidly.

It has a farty little motor driven by a reasonable sized power pack. Totally grief free in 10 years of near continuous operation.

[Guest]

Do you not need the hydraulic system to be pressure tested and certified compliant? I'd assumed there were associated regs in the RCD...

 

The 20% estimate was given by one of the narrowboat hydraulic people, their name and email escape me - something about fixed vane and variable vane perhaps, I want prop speed proportional to RPM so my system would be the simplest but the least efficient, and apparently I'd lose relative efficiency with each PTO, unless I ran two separate systems and hence it starts getting complicated real quick...

Edited January 16, 2016 by dpaws

[keif's mate]

Generally speaking, hydraulic drive does not remove the stern gland from the equation. It is usual to connect hydraulic motor and prop by means of a shaft.

 

I suppose it could be incorporated into an Azipod. Bad for draught, but good for manoeuvrability! If you had an hydraulic system, perhaps an hydraulic bowthruster could be incorporated as well.

[Guest]

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

Edited January 16, 2016 by dpaws

[keif's mate]

Up here on the Broads, as probably any other inland waterway system, hydraulic drives are not part of the BSS. The BSS man might look for evidence of leaks from the pollution point of view but there are no pressure tests or certificates of compliance required.

 

I do not know if hydraulic systems are part of the RCD scheme.

 

By Jove dpaws, that is a crafty looking piece of kit. Never sin the loik on it up yer in Narfik!

Edited January 16, 2016 by keif's mate