bow thruster affect on sailing performance?

[Elessar]

10m yacht. how much would fitting a bow thruster adversely affect sailing performance?

The advantages of having one for short/single handed sailing are obvious. from first principles I can see 3 dissadvantages performance wise:

1) increased form drag due to laminar flow being disturbed due to hole through hull.

2)slight loss of lateral area and hence resistance to leeway due the hole through the hull

3)loss of performance due to added weight of bow thruster plus its own battery, also undesireable affect of weight being distributed in the bow of the boat.

so thats the science. but what does all that actually equate to in a 10m yacht? I put the question to you my yachtie cyber chums as im sure a great many of you have fitted them to such a boat and can report to me first hand on the affect or otherwise on sailng performance.

over to you...

1) with ears on the front the drag is negligible. A good installation will fit these.
2)un measurably small if any
3) you don't have to have a bow battery, you can run appropriately sized cables from the engine battery. Far better IMHO.

 

[Elessar]

I am aware of some yachts who have installed external, removable, bow thrusters.

Now if you want drag, and to ruin the looks of your yacht, get one of those! They cost more than a proper installation too!

 

[Elessar]

Learn to handle the boat properly and save your money then you wont have to worry about loss of performance, or worrying the neighbours etc, come on its only 10m long, and if its a Contessa its not a full long keel.

How patronising. Fine on the east coast but very different in the crowded waters down here. A bow thruster makes certain situations possible, and other situation easier thus reducing stress. Sailing is supposed to be fun.

 

[Elessar]

Unlikely you will be able to mount it far enough below the water line to eliminate cavitation on a 10 meter yacht.

The top of the tunnel needs to be at least 6" below the water line. Can you achieve this ?

Fairing does help with drag. Not an issue IMHO.

Negligible loss of leeway.

In a 10 meter yacht, not at the top of my wish list. 15 meter + yes.

Expensive toy of little use.

Agree with all except the depth bit. Half a tunnel diameter is the minimum, with a best practice of 1 tunnel diameter. Depends on thruster size specced, but definitely not 6".

Yet it will have little use, but when it's used it is worth every penny. There are loads of things on the boat you could say that about.

And it's fine that's it's not on your wish list, but the reduced stress is welcome for many cruising crews.

 

[Tom Price]

NO and a thousand times NO!
Running cables aft makes sense but do install a specific battery just for the job. Mine ran off the domestic battery and when that failed . . .see my River Seine to Rouen post!

IF you're committed to the thruster option then note that many are underpowered, while some can only be used for 10 seconds before blowing a fuse; research is essential before you buy.

 

[contessaman]

Learn to handle the boat properly and save your money then you wont have to worry about loss of performance, or worrying the neighbours etc, come on its only 10m long, and if its a Contessa its not a full long keel.

thanks for the advice! i've only been sailing all my life. what would I know eh?
did you read the thread? im not talking about a contessa and why do you assume its a 32 (keel config) if I was? JR made everything from trad long keelers to IOR racers with high aspect fins.

I obviously need to be so skilled like you that I could get a motor sailer with lots of windage and not so much below the waterline and poor reverse steering characteristics in and out of a x-wind berth with a strong wind without my crew (wife) having to do a thing. Perhaps you could give me some lessons since I didn't pick it up on my yachtmaster course all those years ago. My school must have been a bit backwards as they overcame these problems by warping and springing the boat off. I'll see if I can get a more up to date course that teaches me how to defy the laws of physics..

 

[Tom Price]

Sadly

. . . when you've overcome your parking probs - and I do hope you do - you will be continually frustrated at the poor sailing performance of your motorsailor. I've been there!

 

[jordanbasset]

thanks for the advice! i've only been sailing all my life. what would I know eh?
did you read the thread? im not talking about a contessa and why do you assume its a 32 (keel config) if I was? JR made everything from trad long keelers to IOR racers with high aspect fins.

I obviously need to be so skilled like you that I could get a motor sailer with lots of windage and not so much below the waterline and poor reverse steering characteristics in and out of a x-wind berth with a strong wind without my crew (wife) having to do a thing. Perhaps you could give me some lessons since I didn't pick it up on my yachtmaster course all those years ago. My school must have been a bit backwards as they overcame these problems by warping and springing the boat off. I'll see if I can get a more up to date course that teaches me how to defy the laws of physics..

I can offer you one ,in addition I will throw in how to go faster than the speed of light

 

[Elessar]

NO and a thousand times NO!
Running cables aft makes sense but do install a specific battery just for the job. Mine ran off the domestic battery and when that failed . . .see my River Seine to Rouen post!

IF you're committed to the thruster option then note that many are underpowered, while some can only be used for 10 seconds before blowing a fuse; research is essential before you buy.

I install them Tom. Running them off the engine battery is my preferred choice, with a dedicated battery forward second if the the cable route for the very large cables is too difficult.
Engine batteries are designed for the high current draw of the thruster, and you should only use the thruster with the engine on so you won't flatten it.

 

[contessaman]

. . . when you've overcome your parking probs - and I do hope you do - you will be continually frustrated at the poor sailing performance of your motorsailor. I've been there!

roger that green leader. Im going to hate it. but until somebody builds a deck saloon yacht with inside steering that sails as well as my old boat buts is a doddle to handle and thats within my budget its either a compromise for the family or give up the game. for now anyway. maybe when my baby grows into an able crew member I can buy the swan I always wanted. The moody caught my eye as they do hold their value so should be a fair bet to sell on in the future once wife and child are more keen/able.

it does sail a fair bit better than a motor sailer too I was pleasantly surprised when I had a go (fin version -not tried bilge).

 

[Ridax]

I would recommend the wireless remote if you have a tiller as well, makes single hand docking much easier. We love ours in a Nich 32...

Just curious on what the benefit with a remote control for the bow thruster is. I have seen this option and wondered if it would help me but when I go into the dock I need to be at the helm anyhow, at least to control the forward/backward thrust, so I haven't seen the benefit yet. But I am interested in how others use it, maybe I am missing something.

 

[Poignard]

How patronising.

That's the forum for you!

Ask what time it is and someone will tell you how to make a watch.

Or, more likely, how clever he is because he made one.

 

[SailBobSquarePants]

So this is a matter of seamanship. Perhaps we could learn from a recent post on the MoBo pages:
..."

I suggest that approach, even to the extent of booking an instructor for a short tuition session, rather than consider a bow thruster.

Perhaps we could learn that I basically single hand, as my SWMBO really has no interest in sailing besides cooking in the galley on our Taylor's stove, and lounging on the foredeck in a bikini. She is hopeless at throwing anything, and refuses to step from the boat to the dock unless we are dead stopped. And I doubt your current boat has the turning circle of a full keel boat with a small rudder. And I doubt your boat steps under reverse to nearly the extent as a fixed prop in an aperture.

This is a matter of boat design - older boats where never designed for modern marinas, especially single handed. And frankly I won't have some *** that has never sailed one tell me that if I just had more than my 15 years of experience sailing it would all be easy, even single handed.

 

[SailBobSquarePants]

Just curious on what the benefit with a remote control for the bow thruster is. I have seen this option and wondered if it would help me but when I go into the dock I need to be at the helm anyhow, at least to control the forward/backward thrust, so I haven't seen the benefit yet. But I am interested in how others use it, maybe I am missing something.

A remote has two uses - on a tiller-equipped boat, there often isn't a very good place to put the pushbuttons that will be easily accessible when you are busy docking, or a joystick control that will not result in it snagging lines and clothing. By having a remote control on a lanyard, you can stand where ever you want for maximum visibility and line handling ability. BTW - you do need to fit a wired control for the remote to tap into, so I do have a pushbutton pad by my left knee as well - but to use it I have to duck down and cannot see over the coachroof.

The other use is when docking - if single handing, you can take the stern line to keep the stern in, either by lassoing it from the cockpit around a cleat, or by jumping onto the pontoon. Meanwhile, you have the remote with you to keep the bow on to the pontoon using short bursts when it drifts off - and you can keep it there until you have the stern tidy...and then calmly walk up the boat, take the bow line, and secure it.

 

[contessaman]

Just curious on what the benefit with a remote control for the bow thruster is. I have seen this option and wondered if it would help me but when I go into the dock I need to be at the helm anyhow, at least to control the forward/backward thrust, so I haven't seen the benefit yet. But I am interested in how others use it, maybe I am missing something.

check this out:

http://www.youtube.com/watch?v=ogY8VsgwGv0

doesnt tom cunliffe sail an old gaffer? if he can embrace a remote control bow thruster then we all can

I second what a lot of folk on here are saying. to those of you saying we dont know how to sail you're just wrong. I regularly skipper the work yachts and with a big strong crew I find it rewarding springing off and running lines. However my wife hates being given a fender a boathook or a line to take ashore. she sures hell wont helm the boat while I do it. so why not use the technology. and its true, old boats weren't built to negotiate modern marinas which seem to get tighter by the day. Love to get the so called experts on here to come and give me a demo, all on their own, on the type of boats we are discussing, with a stonking x-wind and current too. Just as long as they agree to pay for the damage

 

[Scotty_Tradewind]

Not need maybe, but they enable you to get into berths/situations that would be impossible without one, no matter how well trained. A very useful tool in the modern crowded marina environment.

+1 since I now have a pontoon berth at my yard which is prone to us being blown onto by Westerlies.
In the past 3 weeks of high winds we still managed to get off by going astern against a spring and a large ball fender to assist the bows coming out and the bowthruster did the rest.
However, for what it cost the previous owner in 2010 to have put in, I doubt if i would have done the same no matter how marvellous it is.

 

[jordanbasset]

I install them Tom. Running them off the engine battery is my preferred choice, with a dedicated battery forward second if the the cable route for the very large cables is too difficult.
Engine batteries are designed for the high current draw of the thruster, and you should only use the thruster with the engine on so you won't flatten it.

That is the same set up as on our boat.
When we first bought her I questioned the need for bow thrusters on a 12 metre boat but it does make things so much easier on a few occasions. Probably would not have fitted it myself but would not remove it now

 

[Tranona]

You seem almost there in adjusting to the new mindset. Still can't quite see the relevance of windward performane as I am sure thrashing to windward is very low on the enjoyment scale for your wife and child! The Moody has a decent engine - maybe overpowered with a 43hp - and it is there to be used.

I am sure you will learn to adjust your strategies to take into account your new ambitions. You have probably chosen the best boat for the job (at least at an affordable price) The marginal difference in sailing performance (if there is any) with a bow thruster will be just that - marginal. A fixed prop will make a bigger difference, so a feathering prop should be on the wish list. Decent sails will of course also make a big difference.

The key to success in buying such a boat is to buy the very best you can in terms of condition and equipment. You have no control over the basic characteristics of the boat. That way you are giving the boat the best chance of doing your job. It also means that if, after a couple of years you decide that family sailing is not working you will be able to sell easily without losing your shirt.

 

[contessaman]

You seem almost there in adjusting to the new mindset. Still can't quite see the relevance of windward performane as I am sure thrashing to windward is very low on the enjoyment scale for your wife and child! The Moody has a decent engine - maybe overpowered with a 43hp - and it is there to be used.

I am sure you will learn to adjust your strategies to take into account your new ambitions. You have probably chosen the best boat for the job (at least at an affordable price) The marginal difference in sailing performance (if there is any) with a bow thruster will be just that - marginal. A fixed prop will make a bigger difference, so a feathering prop should be on the wish list. Decent sails will of course also make a big difference.

The key to success in buying such a boat is to buy the very best you can in terms of condition and equipment. You have no control over the basic characteristics of the boat. That way you are giving the boat the best chance of doing your job. It also means that if, after a couple of years you decide that family sailing is not working you will be able to sell easily without losing your shirt.

ah, thanks! you must remember my previous threads! the old boat is sold so thats the (dare I say it) hard bit over. It hurt me to let her go. just got to find the right example of the above class now. I must admit (probably as im used to racing yachts) they all seem in good condition and well equipped. still got an urge to look at a few other classes of yacht that tick the right boxes before comitting. I'll probably buy this winter next spring - if I can wait until then then I should be able to buy outright rather than farting about with loans or mortgages. that said when the right boat crops up you just have to go for it dont you! like a child in a sweet shop!

 

[Tranona]

Yes, they will mostly be good because they attract serious owners who look after them. So it does come down to trying to get the best balance of equipment. You will probably find you have to go for it as soon as you find one that close to your ideal. Good Luck