Dutch Barge Power requirement

[Mathilde]

Dear All
I recently bought a 1920 Dutch Barge in France. It needs a complete refit including the entire propulsion system. When finished it will displace approximately 70-100 tonnes, its hull length is 28 metres with a 5 metre beam and a blunt bow. I need to achieve a max speed of ~7 knots to pass a Rhine certificate but it will normally need to cruise around 3-5 knots. It will be limited to cruising the inland canals and rivers of Europe. I need advise on propellor size/design and engine power torque required to both achieve the max speed but also have easy cruising. I was thinking of a hybrid system. Expert opinions would be greatly appreciated.
By the way my name is Matthew, the Barge is named Mathilde!

[Ad Hoc]

Welcome Matthew,

You're going to need to provide far more info than you currently have. To estimate the power requirements is the "easy" part...that would be around 70kW. But the rest depends upon so may other factors, which can be provided with a GA and a rough lines of the stern and where you wish to location the prop etc.

Hybrid system adds even more complication dependent upon even more data, which you not provided. It influences the efficiencies and when the power is delivered and at what rpms etc..

So, stick to basics first, the estimated power would be in the realm of 70kW (but without seeing a GA is just a guide). Then see if this fits your size/budget/tastes/whims etc..and go from there.

Baby steps first!

[Mathilde]

Dear Ad Hoc
thank you for the very prompt reply. First baby step is fine. I was advised by an experienced barge captain ~120hp would be sufficient so that ties in. I was thinking of a DAF / Deuetz diesel as the main engine. Then the reason I was thinking an electric addition is as follows
1) it currently has a prehistoric ~30HP Industralie 2 stroke slow speed engine in it and it cruised in pre purchase trials very happily at canal speeds. So thats all I need for canal cruising
2) I need more power to get up to 13 km/hr which is the min speed I need to pass a Rhine certification
3) I was concerned that regular use of a main engine at idle speed (all I would need to cruise) would end up glazing bores and be generally inefficient
4) I like the idea of silent cruising on occasion
I fully understand however on big tidal rivers then its a different matter so the original engine and gear box will go for something more modern.
Can you advise what other information I will need to get a better idea of engine prop requirements. Sorry dont know what GA stands for. Just for fun I tried an online prop calculator and it helpfully said I needed a 41" prop! Hmm

[Ad Hoc]

GA stands for General Arrangement. Here is one GA iteration i did several years ago for a client, as info.



What it needs is to show the location of the engines/shaft line, and then a Lines Plan, showing the shape of the hull, especially aft, where the prop is located, to see how the flow of water is to the prop.

Your prop is best suited to ensure you get your top speed, then see what power is available, from whatever method you prefer to cruise at, and see what speed you'll get with that power using the prop which has been selected for the higher speed; since the efficiencies will be different.

Thus, if you also have a resistance curve for the boat, would be nice to confirm.

[Mathilde]

Many thanks. I have some basic dimensions and profiles of the hull , I will put them into a drawing and post shortly. perhaps that will be of some use
Matthew

[FAST FRED]

I would look carefully at ALL the engine graphs that most engine MFG post with their engines.

There is usually a very high output graph , that can only be used for very limited time.

I would try to match that limited output rating to the high speed requirement for power.

You can then pass the speed test , and have far less worries about underloading in normal cruise.

One of the Fiat Ivecio units would look good for this.

The choice would depend on parts in your area.

I would first get the dimensions of the existing prop, and shaft , to see weather they are able to handle the power required for the high speed demonstration, or if they too need replacing.

A CPP ( Controlible Pitch Prop) would be first choice if all the stern gear needs replacing.

It will help load the engine and give better life and fuel burn at Slo cruise.

FF

[Mathilde]

Many thanks Fast Freddie. Good points