Eco-Hull by ABC Boat Building

[Hornblower]

Hello,

 

I recently found an unusual bow-design on the web: Eco-Hull by ABC Boat Building.

 

http://www.abcboatbuilding.com/extras.html (scroll down)

 

It seems to have some hydrodynamic advantages, so it should be interesting for intensive cruising boats (hireboats and continous cruisers). But I think I have never seen one on the canals (even not on ABC hireboats). Is it new? Is it to expensive to build? Is it because of the nontraditional look?

 

Has someone here such a bow?

 

Cheers

Hornblower

[Athy]

No, it is not new; it came out six or seven years ago. There was something in the boatimags about it at the time. I am not sure if it caught on, or whether the option is still available.

[Sea Dog]

I think there's been a thread on this before - a search may turn something up. Certainly the bulbous bow is in extensive use at sea, mainly due to its beneficial effect on fuel usage. Hard to see whether you'd get your investment back when you only burn a litre and a half an hour though.

[GUMPY]

"eco" hulls came out about 20 years ago. They don't work as well as claimed on the canal, fine in open water which is where the design was adapted from. A decently designed hull with double curved swims fore and aft (ala GU motor style) produces less wash/disturbance for a given speed through the water, trials were done at the time.

Unfortunately most boat builders seem incapable of building anything like that; I.e if you you can't see it it can be as basic as you can get away with.

Modern narrowboats with double curved swims are as rare as rocking horse poo.

Edited December 19, 2016 by Loddon

[cuthound]

I seem to recall ABC saying that it didn't save the anticipated amount of fuel, because the hirers simply took advantage of the better hull dynamics to travel faster.

[Tonka]

My neighbour has one and they do work. They were so successful that they could put a smaller engine in then normally specified but then they found that the stopping power was not enough. The will only put them on private boats now

[Athy]

My neighbour has one and they do work. They were so successful that they could put a smaller engine in then normally specified but then they found that the stopping power was not enough.

...especially when, as Cuthound notes, hirers of these boats drove them faster than they would have driven a conventional boat.

[Nightwatch]

Get a nice big water tank in there.

[Hornblower]

...

A decently designed hull with double curved swims fore and aft (ala GU motor style) produces less wash/disturbance for a given speed through the water, trials were done at the time.

Unfortunately most boat builders seem incapable of building anything like that; I.e if you you can't see it it can be as basic as you can get away with.

Modern narrowboats with double curved swims are as rare as rocking horse poo.

 

Interesting point, is a double curved swim really better than a straight one?

 

I know that long swims are better but not often used with short boats because of the space inside. But if you ignore the missing space, would a long swim on a short boat have disadvantages with stability (rocking,...)?

[GUMPY]

 

Interesting point, is a double curved swim really better than a straight one?

 

I know that long swims are better but not often used with short boats because of the space inside. But if you ignore the missing space, would a long swim on a short boat have disadvantages with stability (rocking,...)?

Well....... Loddon is 60ft and has a front swim that finishes in the cabin and that's with a 5ft well deck never actually measured it, rear swim finishes somewhere under the bed ( normal trad stern no engine room ) technically its not "double curved" but is also not slab sided like most boats are now.

Yes I would say that Loddon is slightly more tender than my previous 60ft NB but makes up for that by slicing through the water.

Struggle to post pics from mobile but here are some links.

Bow

https://www.dropbox.com/s/oqe1swyeq9g6zik/2012-07-24%2010.53.18.jpg?dl=0

https://www.dropbox.com/s/6d3k7sstbetayh7/2012-07-24%2015.11.24.jpg?dl=0

Stern

https://www.dropbox.com/s/i5ni6z3vobipm5f/2012-07-24%2010.56.35.jpg?dl=0

https://www.dropbox.com/s/jcr04gzqymgpxpl/2012-07-24%2010.56.17.jpg?dl=0

As you can see the base of the stern swim is narrower than the top.

After a lifetime on boats of varying types I can easily say Loddon "swims" better than any other boat I have had or steered.

[Old Son]

I've got one of these Eco Hulls. I thought it was supposed to cut down on wake. It doesn't, it makes it worse. Its nothing like the extended bows they add to sea going ships, I can post photographs if you wish but there was a thread on this some time ago.

[Paul C]

Have I got the physics right, the forces imposed (and thus the fuel required to overcome the drag) is proportional to the square of the speed? Thus, a 10% fuel saving can be achieved by travelling 4.9% slower?

[Dalslandia]

Have I got the physics right, the forces imposed (and thus the fuel required to overcome the drag) is proportional to the square of the speed? Thus, a 10% fuel saving can be achieved by travelling 4.9% slower?

Drag increase with the square of speed, but thrust is reduced with speed, so power needed is increased with cube of speed.

[Hornblower]

Well....... Loddon is 60ft and has a front swim that finishes in the cabin and that's with a 5ft well deck never actually measured it, rear swim finishes somewhere under the bed ( normal trad stern no engine room ) technically its not "double curved" but is also not slab sided like most boats are now.

Yes I would say that Loddon is slightly more tender than my previous 60ft NB but makes up for that by slicing through the water.

Struggle to post pics from mobile but here are some links.

Bow

https://www.dropbox.com/s/oqe1swyeq9g6zik/2012-07-24%2010.53.18.jpg?dl=0

https://www.dropbox.com/s/6d3k7sstbetayh7/2012-07-24%2015.11.24.jpg?dl=0

Stern

https://www.dropbox.com/s/i5ni6z3vobipm5f/2012-07-24%2010.56.35.jpg?dl=0

https://www.dropbox.com/s/jcr04gzqymgpxpl/2012-07-24%2010.56.17.jpg?dl=0

As you can see the base of the stern swim is narrower than the top.

After a lifetime on boats of varying types I can easily say Loddon "swims" better than any other boat I have had or steered.

 

Thanks for the pics. Your bow and stern are not only efficient, they also look very elegant. Who built the hull?

 

As bow for my narrowboat I often immagined a river-inspection-launch-style one (very sharp). How would that behave compared to a normal bow?

[GUMPY]

 

Thanks for the pics. Your bow and stern are not only efficient, they also look very elegant. Who built the hull?

 

As bow for my narrowboat I often immagined a river-inspection-launch-style one (very sharp). How would that behave compared to a normal bow?

Loddon was built by Malcolm Pearson.( http://www.malcolmpearson.co.uk ) fitted by Phoenix in coventry, second to last boat that Malcolm ever built.

I always wanted a Phoenix boat the fact that the hull was MP was a real bonus.

[Iain_S]

 

(snip)

 

As bow for my narrowboat I often immagined a river-inspection-launch-style one (very sharp). How would that behave compared to a normal bow?

I used to drive one like that. Handled pretty well, although it's difficult to compare with other boats as it has wheel steering and the distance between rudder and propellor is a bit more than usual.

 

Was really crap in ice, though. Anything more than about a quarter inch thick and the boat became unsteerable, with the bow following the cracks in the ice.

[Jess--]

Well....... Loddon is 60ft and has a front swim that finishes in the cabin and that's with a 5ft well deck never actually measured it, rear swim finishes somewhere under the bed ( normal trad stern no engine room ) technically its not "double curved" but is also not slab sided like most boats are now.

Yes I would say that Loddon is slightly more tender than my previous 60ft NB but makes up for that by slicing through the water.

Struggle to post pics from mobile but here are some links.

Bow

https://www.dropbox.com/s/oqe1swyeq9g6zik/2012-07-24%2010.53.18.jpg?dl=0

https://www.dropbox.com/s/6d3k7sstbetayh7/2012-07-24%2015.11.24.jpg?dl=0

Stern

https://www.dropbox.com/s/i5ni6z3vobipm5f/2012-07-24%2010.56.35.jpg?dl=0

https://www.dropbox.com/s/jcr04gzqymgpxpl/2012-07-24%2010.56.17.jpg?dl=0

As you can see the base of the stern swim is narrower than the top.

After a lifetime on boats of varying types I can easily say Loddon "swims" better than any other boat I have had or steered.

looks quite similar in swim length to our boat (Stenson / MCC) although we seem to have more of a lift to the baseplate at the bow

 

[Athy]

I used to drive one like that. Handled pretty well, although it's difficult to compare with other boats as it has wheel steering and the distance between rudder and propellor is a bit more than usual.

 

Was really crap in ice, though. Anything more than about a quarter inch thick and the boat became unsteerable, with the bow following the cracks in the ice.

THis reminds me, through association of ideas, of what Sheffield people used to say about the locally-built Jowett cars, whose early models were noted for their thin wheels and tyres: "Get in't tram lines and tha'll go all t'way to t'depot".

[Richard Fairhurst]

I seem to recall ABC saying that it didn't save the anticipated amount of fuel, because the hirers simply took advantage of the better hull dynamics to travel faster.

 

Yes. I think the engineers nicknamed them "go-faster hulls" as a result.

[GUMPY]

looks quite similar in swim length to our boat (Stenson / MCC) although we seem to have more of a lift to the baseplate at the bow

 

stern.JPG

The major difference us that your stern swim sides, as most modern narrowboats are, are vertical.......

[nebulae]

I dont know the technicalities of it,but a finer swim,therefore less boat in the water must create less boyant hull. Therefor,less ballast will be required,therefore the boat will be lighter.therefore the boat will be easier to start and stop? Our present boat is on the narrow side at 6ft 9in with the sides tapering in . Under the floorboards,there is one layer of paving slabs,with no ballast under the first two 2ft sections under the floorboards. I would think this is less than most 50ft boats. I have followed a number of threads about the efficiency of water flow around the swim and the bow,but nothing about reducing the boyancy As an example will a Springer with a V bottom require less ballast than a flat bottom boat?

[GUMPY]

Ballast what ballast?

Loddon has no extra ballast, just a slightly thick base plate (15mm)

[nebulae]

Any idea how much 50ft of 15mm baseplate weighs? I seem to remember that one of the operators of working boats said that on a 70ft boat,it will drop 1" per ton?

[GUMPY]

Any idea how much 50ft of 15mm baseplate weighs? I seem to remember that one of the operators of working boats said that on a 70ft boat,it will drop 1" per ton?

Half as much again as a 10mm one

For 15m x 2.1m

3.7T for 15mm plate

2.49T for 10mm plate

So about 1.25T heavier

Edited December 20, 2016 by Loddon

[nebulae]

I guess that makes explains why you dont need extra ballast. Our boat has a bit of age about it,so has a 6mm bottom. Extrapolating from your figures the bottom of our boat weighs one and a half tonnes.,probably more than the ballast. So,if we had the bottom plated,we would have to take out all the ballast.On this basis,you could say that an average leisure narrow boat does not have a lot of extra boyancy in relation to its net weight. Our first steel boat had a clever stepped bottom on a 30ft boat. Because of the reduction in immersed boat,no ballast was needed,the boat was not "tender"and swam well.