Which Bow Thruster?

SgtColon

SgtColon

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Nr Manchester / boat at Cap D'Agde, France
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Last year on several occasions I found it very difficult to reverse onto my pontoon finger berth due to a current and / or wind blowing the bow to such extent that it took several hair raising attempts to complete the manoeuvre. I have to reverse in or there would be no room to get off the boat. I became convinced that I could hear those bloody ducks laughing at my frustration. I have decided to have a bow thruster fitted to reduce the entertainment value for spectators and to eliminate that ridiculous feeling of ‘should I go out in case its difficult to get back in.’
The boat is a Sealine S23 (7.62m / 25’ sports cruiser) with a single duoprop. It has a single port battery for starting and two starboard batteries for domestic use. Money is inevitably a consideration but I don’t want to underpower the thruster. I’m assuming the correct tunnel will be 125mm but I’d be interested in the experiences and advice of similar boat owners. I’ve read in the advertising that a thrust force of 25kgf is suitable for a boat length of 5.5m to 8.5m and 35kgf for a boat length of 6.5m to 10m.

I was thinking of maybe one by Phoenix which is 12v 250 amp 35kgf 2.2kw 3hp
BUT they also do a 55kgf 4hp one. Would this power be a disadvantage? I don’t think the additional weight will be a problem. I’d welcome your thoughts.

Graham
 
The thing about a bowthruster is that when you really really need it, it's because it's blowing a hoolie so there really is no point in getting an undersized one, especially in your case with a single engine. The other major issue is where to locate it because obviously it needs to be as far forward as possible for maximum leverage but also as deep as possible so it doesn't aerate and also located so as not to conflict with bulkheads and furniture. These people have fitted a Sleipner Side Power bowthruster for me some years ago and they were excellent so worth at least talking to http://www.osmotech.co.uk/bow_thrusters
 
I hve a SidePower 55 thruster fitted to my 7t 36ft sailboat and that gives a very good kick and moves the boat under most circumstances I have tested. Its attached to an 85ah dedicated battery. Years back I had the smaller one the 40 I think, on a 28ft single OD sports MOBO and that always did the job admirably and gave that extra security when it was blowing a bit. On the sail boat with its fin keel and huge rudder I very rarely use it, but on the MOBO, it was a useful tool in regular use. The only issue I had with fitting it to the MOBO was not the tunnel and motor - they went in fine, it was where to put the battery. The further away you have it from the motor, the bigger the cables get. Mine was about located 3m away in the end and needed massive and I mean massive, cabling. As has been said, be worth speaking with Osmotech in the first instance.
 
SgtColon said:
Last year on several occasions I found it very difficult to reverse onto my pontoon finger berth due to a current and / or wind blowing the bow to such extent that it took several hair raising attempts to complete the manoeuvre. I have to reverse in or there would be no room to get off the boat. I became convinced that I could hear those bloody ducks laughing at my frustration. I have decided to have a bow thruster fitted to reduce the entertainment value for spectators and to eliminate that ridiculous feeling of ‘should I go out in case its difficult to get back in.’
The boat is a Sealine S23 (7.62m / 25’ sports cruiser) with a single duoprop. It has a single port battery for starting and two starboard batteries for domestic use. Money is inevitably a consideration but I don’t want to underpower the thruster. I’m assuming the correct tunnel will be 125mm but I’d be interested in the experiences and advice of similar boat owners. I’ve read in the advertising that a thrust force of 25kgf is suitable for a boat length of 5.5m to 8.5m and 35kgf for a boat length of 6.5m to 10m.

I was thinking of maybe one by Phoenix which is 12v 250 amp 35kgf 2.2kw 3hp
BUT they also do a 55kgf 4hp one. Would this power be a disadvantage? I don’t think the additional weight will be a problem. I’d welcome your thoughts.

Graham
Click to expand...

I'm in the process of fitting a Vetus 35 KGF to my Sealine 218 in a 150mm tunnel, that will be more than adequate
 
I have a Vetus 25Kgf on my single prop 24 cruiser and it works fine though never really tested it over a Force 4. I reverse into my berth and use it every time as I do also getting in and out of the pontoon in the lock. It has a dedicated battery in the bow right next to the motor that powers the thruster and the windlass.

Suppose if you are starting from scratch bigger is better.
 
30kgf on a 25 foot Bayliner worked very well. Could almost knock someone off balance on the foredeck if they weren't prepared for it :-) I would say always go as big as possible, nothing worse than an underpowered thruster. I would rather not have one at all. Mine was a QL BP300 with a 132mm tunnel.
 
I agree with all, if in doubt go large! We had a SeaRay 315 with single duo prop plus side power bow thruster fitted by Osmotec, brilliant and reassuring bit of kit.

As for wiring there is a balance between the cost of the massive cables vs cost of extra gel type battery mounted adjacent to thruster which then only needs modest wires from the engine for charging. Of course lack of forward space may mean you are unable to mount a forward battery.

If you supply the power from the existing batteries my preference is to power it from the engine start battery, that way if you flatten you domestic battery bank when away you can still start the engine and manoeuvre away from your berth.
 
Graham, don't do it!!

How long have you that lovely S23 now? Maybe it's time to upgrade to an S28 with a bow-thruster. Tryben is a lovely boat, i'm sure you'd easily find a new owner considering that she's an absolute minter!
 
aquapower said:
I'm in the process of fitting a Vetus 35 KGF to my Sealine 218 in a 150mm tunnel, that will be more than adequate
Click to expand...

I would agree and say that is about right for an S23,
I have a 255 and a Sidepower 40. installed.
The only problem I had was getting it low enough, and avoiding the table leg.
Both of these problems were overcome, and I have enough power for all the conditions that I use the boat in.
I agree with other posters, you need the battery as close as possible, and gel is best.
 
SgtColon said:
Last year on several occasions I found it very difficult to reverse onto my pontoon finger berth due to a current and / or wind blowing the bow to such extent that it took several hair raising attempts to complete the manoeuvre. I have to reverse in or there would be no room to get off the boat. I became convinced that I could hear those bloody ducks laughing at my frustration. I have decided to have a bow thruster fitted to reduce the entertainment value for spectators and to eliminate that ridiculous feeling of ‘should I go out in case its difficult to get back in.’
The boat is a Sealine S23 (7.62m / 25’ sports cruiser) with a single duoprop. It has a single port battery for starting and two starboard batteries for domestic use. Money is inevitably a consideration but I don’t want to underpower the thruster. I’m assuming the correct tunnel will be 125mm but I’d be interested in the experiences and advice of similar boat owners. I’ve read in the advertising that a thrust force of 25kgf is suitable for a boat length of 5.5m to 8.5m and 35kgf for a boat length of 6.5m to 10m.

I was thinking of maybe one by Phoenix which is 12v 250 amp 35kgf 2.2kw 3hp
BUT they also do a 55kgf 4hp one. Would this power be a disadvantage? I don’t think the additional weight will be a problem. I’d welcome your thoughts.

Graham
Click to expand...

You need someone to teach you how to Park it properly I reckon:p:D
 
Dill et Bound said:
I would agree and say that is about right for an S23,
I have a 255 and a Sidepower 40. installed.
The only problem I had was getting it low enough, and avoiding the table leg.
Both of these problems were overcome, and I have enough power for all the conditions that I use the boat in.
I agree with other posters, you need the battery as close as possible, and gel is best.
Click to expand...

I put mine in the locker forward of the table leg under the seat, there was loads of room, I'm also fitting a seperate battery for thruster/winch and swapping other 2 batteries for AGM aswell.
 
Kawasaki said:
You need someone to teach you how to Park it properly I reckon:p:D
Click to expand...

You mean I need someone proper to teach me how to park it ....... Nah you didn't do a bad job. I've crashed into things just like you showed me .... You can't be blamed for the unusual microclimate of PD pontoon marina and it's tropical currents .... But it's those ducks, they're watching and laughing all the time.
 
alt said:
Graham, don't do it!!

How long have you that lovely S23 now? Maybe it's time to upgrade to an S28 with a bow-thruster. Tryben is a lovely boat, i'm sure you'd easily find a new owner considering that she's an absolute minter!
Click to expand...

You're right Niall, She's still a gem but the South of France still beckons in a couple of years so I might as well wait to upgrade then.
 
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