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Bill H

So you want to build/buy a boat in the PH, here is the place to discuss it!

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colemanlee

 

 

That said, I think the growing alternative today is diesel electric propulsion

 

Interesting its a "growing alternative" knowing nothing about today's preferences, I would have thought Submarines would have proved this propulsion system years ago?

 

Great thread, lots of interesting info

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Oz Jon

Interesting its a "growing alternative" knowing nothing about today's preferences, I would have thought Submarines would have proved this propulsion system years ago?

 

Great thread, lots of interesting info

Submarines and other "big boats" can afford the big volume and weight of (conventional, 20th century) high power generators and motors - smaller vessels/yachts cannot.

 

The availability these days of much lighter weight, more efficient generator and motor designs plus smart electronic controllers, is changing the playing field.

 

eg. A conventional 20HP motor weighs 200-300lbs, a 60HP hydraulic gear motor (or pump) is about 1/10 of the size and 1/10 weight.

Edited by Oz Jon

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Soupeod

So how much is a fair price for a little two seat boat for close to shore fishing and exercise? I've been wanting to buy one but don't want to pay too much. In the USA I could buy a small sea kayak for less than 200. Any chance of getting one built for that here?

 

Needs:

2 seats

Fishing

Daily exercise paddling.

As small as possible to be able to launch by hand alone.

 

I bought one for my father in law after his took its last cruise, very small, local village boatcrafter made it about $500 16ft or so..  They are all over.

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richard_ost

eg. A conventional 20HP motor weighs 200-300lbs, a 60HP hydraulic gear motor (or pump) is about 1/10 of the size and 1/10 weight.

 

You still need a power source (combustion engine) to operate the hydraulic pump. So the whole hydraulic system adds extra weight compared to propulsion system where you take the power straight from the engine to the propeller (via gearbox).

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Bill H

You still need a power source (combustion engine) to operate the hydraulic pump. So the whole hydraulic system adds extra weight compared to propulsion system where you take the power straight from the engine to the propeller (via gearbox).

 

Yes that is true, but the gearbox is not exactly light.  I think the heaviest part of a hydraulic system is probably the hydraulic fluid itself (depending on how much you carry).  In any case it would certainly be lighter than two stand alone engines with their gear boxes, I don't see any argument about that.

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Oz Jon

You still need a power source (combustion engine) to operate the hydraulic pump. So the whole hydraulic system adds extra weight compared to propulsion system where you take the power straight from the engine to the propeller (via gearbox).

You really need to take an overall view of any proposed system. Consider all the factors.

 

For a simple 1-engine, 1-prop requirement, all-mechanical, gearbox and CV jointed shafts is the way to go.

 

But,

 

eg.in my catamaran example -

A single-engine, all-mechanical solution would have been "a sight to behold"!

 

[at least 2 shaft direction changes for one hull and at least 4 for the other hull -

 

and a complex power-splitter gearing/clutch thing to give independence for each hull?]

 

the mind boggles!

 

I could have sold tickets to have a look at it - Lol!

 

Horses for courses!

 

The viable options were 2 engines or my hydraulic solution.

Edited by Oz Jon
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Oz Jon

Richard, are you the Oz guy (that I met at Drydock, Carmen) who had an electric motor (battery/solar/diesel) driven mono-hull yacht?

 

It was impressive, but had only limited HP and lots of batteries with the technology then available.

Edited by Oz Jon

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thebob

I think the thing to take into account is not reinventing the wheel. In a cat only power one hull, then the other one is cleaner and quieter.

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Oz Jon

I think the thing to take into account is not reinventing the wheel. In a cat only power one hull, then the other one is cleaner and quieter.

Sounds good Bob, but I've had a situation where one propshaft was bent and unusable, so I had drive on only one hull.

 

Very tricky to control, before the boat was moving forward fast enough (about 3kts) for the rudders to work effectively to counter the powerful turning moment.

 

I was forced to do about a 90 degree accelerating turn before getting enough speed up to have rudder control.

 

No problem at sea, but that's not easy to deal with in tight spaces!

 

If you only have 1 prop, it needs to be central!

Edited by Oz Jon
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AussieLex

Lots of Wharram cats have a central deck mounted single diesel with a long shaft that can be raised and lowered as needed making for cleaner water when sailing. 

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richard_ost

You really need to take an overall view of any proposed system. Consider all the factors.

 

For a simple 1-engine, 1-prop requirement, all-mechanical, gearbox and CV jointed shafts is the way to go.

 

But,

 

eg.in my catamaran example -

A single-engine, all-mechanical solution would have been "a sight to behold"!

 

[at least 2 shaft direction changes for one hull and at least 4 for the other hull -

 

and a complex power-splitter gearing/clutch thing to give independence for each hull?]

 

the mind boggles!

 

I could have sold tickets to have a look at it - Lol!

 

Horses for courses!

 

The viable options were 2 engines or my hydraulic solution.

 

Sorry, didn't read your first post well enough. Sounds like an interesting solution :). With only one engine that sounds like a smart idea. I prefer electric motors but with your scenario the hydraulic system sounds like a good idea. I'd also rather have that system compared to one shaft in the middle.

 

 

Richard, are you the Oz guy (that I met at Drydock, Carmen) who had an electric motor (battery/solar/diesel) driven mono-hull yacht?

 

It was impressive, but had only limited HP and lots of batteries with the technology then available.

 

No :). I'm from north Europe.

 

I'm very interested in solar/electric-propulsion systems, specially with catamarans. The commercial versions are still in very early stages but you can always build your own. Batteries are still heavy, unless you have the money to buy Lithium batteries. But even with Lithium batteries the energy content per weight is ridiculous 100W/kg compared to gasoline (output power to the shaft) around 2000-3000W/kg. With a "light" cataman (low drag resistance) you can already have a nice cruising speed with a very small power (LWL=10m, mLDC=3000kg, speed 6kn, installed power 3kW). And if you get solar panels (15% efficiency) you get 1kW from every 6,5m2 . If I ever went with electric propulsion, I'd probably go with some pod-unit that wouldn't make as much noise as the commercial electric outboards that are out there at the moment. And you can build your own cheaper, if you don't put any value to the time you sacrifice with the project :) .

Edited by richard_ost
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bluecarabao

I found a very nice design for a catamaran on the internet and apparently one is already on the water's of the Philippines. You purchase the plans and go from there
http://bateau.com/proddetail.php?prod=SK28#.VklbPb925QU  new plans available are for a 30' and a 36'    http://bateau.com/studyplans/SK28_study.php?prod=SK28
Looks like it is very economical to run, and very stable. It would mostly be used as a passenger and cargo hauler.
Here is a video 

and 


Electric powered catamaran 

  Electric Drive System   

  Hybrid Propulsion      

 

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thebob

 

 

 

Thanks for that link... on the same site is the D4 free plans.

 

http://bateau.com/free/D4.pdf

 

I built one of these and have another as a tender. They are cheap and easy to build and very good practise for stitch and glue construction. Mine uses an old windsurfer sail.

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colemanlee

Wonder if you could build this one out of steel....

 

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AussieLex

You guys might want to check out this site for jarcats ...

 

http://jarcatmarine.com

 

Ross Turner the designer died a couple of years ago but his son is keeping things going... he sells plans for a variety of catamarans and there are many many J5 and J6 catamarans sailing in Australia and some have been built in the USA and Europe as well. Easy to build ... I actually bought a set of plans from him for a J6 a few years ago and modified the design as well as extended the boat to make it more like 7.5 metres long and a bit wider... I sailed that boat along the Queensland coast and lives aboard for almost a year ... Usually sail powered with a single outboard engine s an auxiliary power source .. worth a look.

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