bow thruster rating

[Iggy]

I have a 40' trawler that is around 28,000lbs. I bought it with an SP55 thruster. At 12V should put out 147lbs of thrust.

At the Newport Boat Show a few months ago I was told that it too small for my size boat. That I should go with a the SE80 with at 12v 212lbs of thrust.

There is a SE60 but it only puts out 161lbs of thrust. only 14lbs more. not a real difference. The good thing is the tunnel is the right size for the SE80.

Yes, the SE80 would be better. But is the SE55 considered too small for my size boat? Is the SE60 more in line but most like not worth the money to gain so little? I have looked at the charts, but to me its a general guide.

 

[Bmarler]

Does it work effectively? That’s the real question. If it doesn’t move the bow like you want, upsize it.

 

[Iggy]

Does it work effectively? That’s the real question. If it doesn’t move the bow like you want, upsize it.

Well it does seam slow. But its my first boat with a bow thruster. So I have nothing to compare it to.

 

[CharlieO.]

Was the guy selling thrusters the one that told you your thruster was too small?

 

[Iggy]

Was the guy selling thrusters the one that told you your thruster was too small?

Yep!!

But also looking at the size charts the SE55 is at the end of the range for my size boat. So that too, made me wonder if it was too small.

 

[O C Diver]

I had an older SE 80 and upgraded (switched motor and Props) to an SE 100 when I converted it to 24 VDC. My boat is 45'. For almost anything I do the 80 or the 100 are fine. Pushing my boat off the dock with a 30 knot beam wind isn't possible. Short of increasing the tunnel size (propeller diameter), more HP isn't going to make a difference. The other possible difference is prolonged use. I've only once had the SE 100 temperature limit out after extensive backing in a strong beam wind. The less motor time for each correction, the more corrections you can accomplish.

If you are dependent on the bow thruster for extensive maneuvering when docking, there is certainly advantage to a larger thruster.

Ted

 

[Bmarler]

i would upsize it given the opportunity. my boat is similar size and displacement, and the vetus thruster i have feels a bit underpowered as well. i haven't yet explored what might fit the tunnel i have, but i'm hoping there will be a more powerful one that fits.
i have stern thrusters as well, and i find it to be way more effective at pushing the boat around. i've been a single screw guy all my life though, and pushing the stern is way more intuitive for me so it hasn't really been an issue. it would be nice though, to have the power to push the bow off in higher wind and current.

 

[tpbrady]

I had a 5HP bow and stern thruster on my similar size boat and neither was effective in other than calm conditions. The stern thruster is history as it was hydraulic off the genset which is also history. The bow is electric and I use it rarely as I plan everything around using spring lines off docks or rudder and prop walk going onto docks. 8 is the minimum I would need would preferred being 10.

Tom

 

[Comodave]

Too bad it is so small. I always go with a larger than recommended thruster because it never hurts to have too much power in a thruster. I have not looked up the ratings for the thrusters you referenced but bigger is better. Is it worth the extra money, only you can decide that.

 

[CharlieO.]

Can you get more thrust by upgrading your current prop?

 

[Iggy]

Thank you for all the replays.

Yes, the prop has been changed out.

I called Imtra and they said for $1,400 I can replace JUST the motor and make it a SE60. Just use the same prop. But only 14lbs more thrust.

Four bolts and 2 wires and a connector to change it out. Something i can do easily! SE80 is in the 4k range and I would have to go to a bigger wire and change out the prop assembly. I was will to pay to have it done too. But the company keeps putting me off.

 

[bowball]

I think you are fine. I obsessed over this for a while too, so it’s natural. Looking at the thrust ratings, you are at the upper end given your thrust.

176lbs thrust for sleipner covers 35 to 48’ boats. That’s a blunt tool using length as windage matters and displacement.

Mine is at the upper end too, but it moves the bow fine. For east coast Florida winds maybe hydraulic gets to be important as they don’t time out. But I barely use mine on the west coast. In heavier winds I’m not going to rely on it anyway.

I wouldn’t change it unless you have a reason too. One reason is adding a stern thruster and making sure the controls are compatible with each other if the bow is older.

I would check to make sure you have enough voltage at it though - wiring cable thick enough, battery etc as that will affect the power.

As recommended above, check to see if more modern prop design available. Where they located the tunnel is quite important too.

 

[Comodave]

On our last boat we put a Sidepower stern thruster in it. I went one size larger and it worked great. Once there was 25MPH wind pinning the boat to the dock. The thruster immediately started moving the boat off the dock. I was very impressed.

 

[rslifkin]

I've always figured that if a thruster can't move the boat against a fairly decent wind (somewhere in the 20 - 30kt range), there's no point in having the thing at all. Those windy days are when you're most likely to really need it, as you can't take your time to wiggle the boat around like you can in calm conditions.

 

[Comodave]

I've always figured that if a thruster can't move the boat against a fairly decent wind (somewhere in the 20 - 30kt range), there's no point in having the thing at all. Those windy days are when you're most likely to really need it, as you can't take your time to wiggle the boat around like you can in calm conditions.

Yup.

 

[Arc]

I have an SE60 in my 31 DE. It works wonderfully. No way would I want it in a 40’ boat

 

[O C Diver]

Thank you for all the replays.

Yes, the prop has been changed out.

I called Imtra and they said for $1,400 I can replace JUST the motor and make it a SE60. Just use the same prop. But only 14lbs more thrust.

Four bolts and 2 wires and a connector to change it out. Something i can do easily! SE80 is in the 4k range and I would have to go to a bigger wire and change out the prop assembly. I was will to pay to have it done too. But the company keeps putting me off.

Shop the price. Imtra is the distributor and doesn't discount the price to protect their dealers. Did much better going through a dealer. Wouldn't recommend that dealer. You might give Defender.com a call. They are a distributor for Side-power and have good prices on the accessories and consumables. They maybe able to sell you the motor.

Ted

 

[O C Diver]

I've always figured that if a thruster can't move the boat against a fairly decent wind (somewhere in the 20 - 30kt range), there's no point in having the thing at all. Those windy days are when you're most likely to really need it, as you can't take your time to wiggle the boat around like you can in calm conditions.

I usually avoid situations where it's needed in 30 knot winds. For me, the thruster is most valuable in tight situations where wiggling isn’t an option. Going into a smaller lock where there are boats already on one side would be a good example.

Ted

 

[Derek]

We have a 43’ Mainship and just had a SE80 installed and went 24v w/ (2) 4D batteries under the aft bed with a dedicated 10 Amp charger wired off a not used washing machine plug in the engine room instead of the outlet by the bed. Now when using our inverter, the batteries will not have to use its energy for charging. I just keep the washing machine circuit closed and can still use all the outlets. Very pleased with the solution.

 

[Mike3034]

I have a 40' trawler that is around 28,000lbs. I bought it with an SP55 thruster. At 12V should put out 147lbs of thrust.

At the Newport Boat Show a few months ago I was told that it too small for my size boat. That I should go with a the SE80 with at 12v 212lbs of thrust.

There is a SE60 but it only puts out 161lbs of thrust. only 14lbs more. not a real difference. The good thing is the tunnel is the right size for the SE80.

Yes, the SE80 would be better. But is the SE55 considered too small for my size boat? Is the SE60 more in line but most like not worth the money to gain so little? I have looked at the charts, but to me its a general guide.

We have a single engine 43' American Tug, 30,000LBS. Have an SP95 on bow and SP55 on Stern with 5 bladed prop. Wouldn't think of having much less on bow or stern. Only use in tight spots and wind/current. 55 is a bit slow on stern even with upgraded 5 bladed prop..

 

[jimdavi]

I have SidePower SE-130’s 24vdc on my 45 North Pacific. Bigger is better. Will always move the boat, if needed.

 

[Comodave]

Sometimes size does matter…