Bow Thruster on a Catamaran

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properjob

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Has anybody fitted a Bow Thruster on a single engined catamaran such as a Prout, Gemini or any other catamaran using a centrally mounted Sonic Drive ? I would imagine that plenty of owners have at times wished that they had, but has anybody using this forum actually fitted one ? I have only ever seen one, that was on a Prout Quest that was ashore in a boatyard for the winter.

I find that manoeuvring my Prout at slow speeds in cross winds can be a bit tricky. I can place the stern pretty well where I want, but in any cross wind I find that the bows pay off to leeward and, in correcting that, the whole boat drifts to leeward. The lack of prop wash over the rudders does not help matters. Therefore I find that I need more space in which to manoeuvre than with previous craft that I have owned, both multihull and monohull.

As I shall be using the French canals next year I can foresee awkward situations occurring where having a Bow Thruster would make life a bit easier.
 
You don't need it to be central. a bow thruster in just one hull will do it and there are several snowgoose's out there who have this setup although you have to get one narrrow enough to go in the space available. The real answer is twin engines though which makes a bowthruster unnecessary.
It is however possible to do what I have done in my Prout 37 and fit a light 10HP engine in one hull with a saildrive. It makes it a bit more complex but you can hold station with the central engine and turn by putting the "wing" engine in forward or reverse. With this set up I can actually pivot in a boats length. It also gives me an option when motor sailing, (or perhaps slow canal motoring) as it has a Brunton Autoprop and doubles as a generator to charge batteries without running the bigun.
If I was starting again though I would fit twin engines. Best of both worlds!
 
Fitting an electric outboard under the foredeck had occurred to me but I think that it would be very vulnerable to heavy seas. As the bows do go under in big seas any outboard in that position would have to capable of total immersion let alone being physically knocked about, any mounting would have to be very strong. I imagine that a system that used an electric outboard that was slotted into place once the catamaran was in sheltered waters might be feasible, its certainly worth looking into.

There is a Canadian system that uses a hinged drive leg on the bows but its rather expensive.
 
Fitted a vetus 55kgf one 5 years ago to a 9m Catalac that has a honda 30 (connected to steering) as the iron mainsail. Has been worth its weight in gold. Allows me to turn on the spot, the same as a cat with engines in each hull.. At present I require 3 hands to operate engine throttle, thruster and steering. I will try to combine thruster and throttle this winter to make it a 2 handed job !!
/forums/images/graemlins/laugh.gif /forums/images/graemlins/smirk.gif
 
I have piccies but don't use any of the 'commercial' site. PM me and I will dig out and send some.
The bow thruster is only in one hull and with hindsight could of been put further forward, but we live and learn - allegedly.
/forums/images/graemlins/smirk.gif
 
I reckon Boatmike's idea of adding an outboard to the stern of one hull would have merit. Especially if you have the o/b already. For manouvring you would need to fit remote controls ie gears throttle and steering but steering need only be fairly crude centre one lock and the other by lever /pulleys. It would all seem easier than cutting a hole for a bow thruster. And fairly easy to remove and make good if you didn't like the idea.

The wide beam should give you a fair bit of control of the cat. olewill
 
Boathook,

How did you size your thruster - we are looking at putting one on our Prout, but the sizing of yours seems rather large for the math we did on our Prout Snowgoose 37.

Geoff.
 
geoff_r said:
Boathook,

How did you size your thruster - we are looking at putting one on our Prout, but the sizing of yours seems rather large for the math we did on our Prout Snowgoose 37.

Geoff.
Click to expand...

The calcs showed around a 40kgf was required. As the vetus 35 and 55kgf both had the same size tubes it made sense to fit the bigger motor as in theory you use it for less time. Knowing what I now do, I would of fitted the unit further forward which would increase performance. The extra power is not wasted and sometimes I want more !!! When doing the calcs if in doupt err on the side of caution to make the worse case.
 
properjob said:
Has anybody fitted a Bow Thruster on a single engined catamaran such as a Prout, Gemini or any other catamaran using a centrally mounted Sonic Drive ? I would imagine that plenty of owners have at times wished that they had, but has anybody using this forum actually fitted one ? I have only ever seen one, that was on a Prout Quest that was ashore in a boatyard for the winter.

...

As I shall be using the French canals next year I can foresee awkward situations occurring where having a Bow Thruster would make life a bit easier.
Click to expand...

How long have you had your prout. Is it the 33 ?

I really stuggled with my Prout 33 to start with in close quarters but after a couple of years have got used to it. Sometime the slowest speed isn't what is needed. Perhaps go in a little quicker than you might to maintain steerage and a sharp bit of reverse (with vectored thrust) to tuck the stern in if where appropriate can do a lot. I am not planning on doing the canals at present but if I was I reckon I would be able to manage without a bow thruster. (I have done a lot of canals/rivers in the past but admittedly not in my Prout)

But (assuming you have a Prout) always check you you have reverse locked in. I think we have all done that...

The other top tip is to master the "Thames style" way of capturing a cleat/bollard by using two thrown arms of line. I am going to struggle to describe this is you don't know what I mean but a day on the Thames and you will see people doing it - it's HIGHLY effective at securing the boat to a cleat from 2 or so metres out. A really useful thing to be able to do.

Best of luck if you do go the bow thruster route.
 
Interested in whether you did fit a thruster. I have a 37' Prout which is difficult to manoeuvre at the best of times but now in a marina with tide and wind which makes it impossible at certain times to get into slip.
 
Yes I did fit a bow thruster, a Max Power CT45 in the starboard hull of my Prout Event that I still have. It's been superb, well worth fitting with minimal maintenance.
 
boatmike said:
You don't need it to be central. a bow thruster in just one hull will do it and there are several snowgoose's out there who have this setup although you have to get one narrrow enough to go in the space available. The real answer is twin engines though which makes a bowthruster unnecessary.
It is however possible to do what I have done in my Prout 37 and fit a light 10HP engine in one hull with a saildrive. It makes it a bit more complex but you can hold station with the central engine and turn by putting the "wing" engine in forward or reverse. With this set up I can actually pivot in a boats length. It also gives me an option when motor sailing, (or perhaps slow canal motoring) as it has a Brunton Autoprop and doubles as a generator to charge batteries without running the bigun.
If I was starting again though I would fit twin engines. Best of both worlds!
Click to expand...

+1 and probably a cheaper as well as a more practical solution.
 
smartmove said:
Interesting. Did you fit the thruster yourself? How do you find the power of the C45?
Click to expand...

I had a professional cut the holes and glass in the tube, cost about £300 which included building up and fairing the area forward of the tube to deflect water away from the tube when sailing normally. I did all the rest. As I also have an electric windlass I fitted a dedicated battery for both tasks and positioned close to both. I chose the CT-45 because of the smaller diameter 125mm thruster tube that was necessary because of the low immersed depth and low beam width of the forward part of the hull. Deciding exactly where to place the tube took quite a while to comply with the fitting instructions. The top of the thruster tube has to be same dimension as the tube diameter below the water line and to get the maximum thrust effect the thruster needs to be as far forward as possible.

I have found the CT-45 to be quite powerful enough for every situation that I have been faced with. Hope this helps.
 
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