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Old 26-08-2012, 23:44   #166
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Re: Hmmmm - Bowthrusters ??

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Originally Posted by minaret View Post
No, no, no. I said a feathering prop gives you MORE propwalk, not less. If you read the quote you would notice this. So I am suggesting that having a good feathering prop used properly in reverse can be similar to having a uni directional thruster, with some practice and planning, without any of the drawbacks of a thruster. In fact just the opposite, it gives you better performance under sail as well. How could you think I'm suggesting that a prop with less propwalk would be beneficial, did you just fail to read the post in question? Or am I just a horrible writer...
Maybe I didn't catch that - let's not assume you're a bad writer. It's much more likely that I read carelessly. But most feathering props in reality give less prop walk, not more. Maybe all of them give less - and this is objectively measured in the various tests.

Besides that, the way a boat behaves in astern depends a lot more on underbody shape than type of prop. All props produce a little side thrust; bulb keel boats with skeg rudders like mine go back pretty straight; long keel boats with attached rudders go back in circles. Whatever the propellor type.

Besides that, prop walk is useful in only very few cases - only when you exactly need to go in that direction. If you need to go straight back or in the other direction, you're screwed. I know well - my last boat was like that. If you are going in and out of one berth which happens to suit your prop walk, then that's great - you use the tools you have at hand. But if you're out cruising in a boat with a lot of prop walk, you often don't have that choice. In my old boat, we were often using elaborate spring lines, or more often simply manhandling the boat out of thight situations. A lot of prop walk is a curse, all in all. And certainly no substitute for a thruster.
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Old 26-08-2012, 23:46   #167
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Re: Hmmmm - Bowthrusters ??

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You have a line of direction for your comment ie the 'experienced person'.

My line of examples was from the outset the charter industry that i've noted on this side of the Atlantic, most have Thrusters, Why?

Because on one hand the hirers group are very average, they fly in with a $150:00 boat licence and a credit card, prop-walk to them would likely mean using a walking stick.

The other group are very decent boaters who recognise the cramped and hectic berthing that occurs, they need all tools to keep clear of the above mentioned hazards.

As always there are many points to a debate, we were surprised to see a Thruster on our cat when we went through the inventory, i accepted it in my mindset once i trialled it using one engine only.

All with catamarans should try to berth their cat with one engine only in mild conditions, it is nearly impossible, as you previously alluded to the boat pivots about that centre. Ain't fun!

Yes whack a dinghy in the water and push the head around is the go but usually things go wrong at the wrong time.

Feathering props, heaps of reverse thrust go hand in hand with a good boat for sure but there are also other tools even 'decent' boaters can add.... Cheers
I can fully understand why all the charter companies just about everywhere tend to have thrusters on their boats, it's the perfect application for them. The boats aren't intended to go very far and are likely to have inexperienced crew. And I'm all for the modern trend in new boats like yours to have a deployable thruster, I've never understood why they cost so much more than a tube thruster. The install isn't that much more complicated. I'm sure it's a great tool to have, I've certainly appreciated them when driving large powerboats before. I just don't think a tube thruster is the best piece of gear for a long range serious cruising sailboat. Sorry if that offends anyone, we all have our opinions and I'm certainly not the only one to have this opinion.
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Old 26-08-2012, 23:54   #168
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Re: Hmmmm - Bowthrusters ??

Quote:
Originally Posted by Dockhead View Post
Maybe I didn't catch that - let's not assume you're a bad writer. It's much more likely that I read carelessly. But most feathering props in reality give less prop walk, not more. Maybe all of them give less - and this is objectively measured in the various tests.

Besides that, the way a boat behaves in astern depends a lot more on underbody shape than type of prop. All props produce a little side thrust; bulb keel boats with skeg rudders like mine go back pretty straight; long keel boats with attached rudders go back in circles. Whatever the propellor type.

Besides that, prop walk is useful in only very few cases - only when you exactly need to go in that direction. If you need to go straight back or in the other direction, you're screwed. I know well - my last boat was like that. If you are going in and out of one berth which happens to suit your prop walk, then that's great - you use the tools you have at hand. But if you're out cruising in a boat with a lot of prop walk, you often don't have that choice. In my old boat, we were often using elaborate spring lines, or more often simply manhandling the boat out of thight situations. A lot of prop walk is a curse, all in all. And certainly no substitute for a thruster.
To each their own. When we call ahead on the radio to a marina to reserve our slip for the night, we always specify a bow-in starboard side tie, because the prop walk will allow us to both enter and exit the slip easily that way. We carefully plan our entrance into the marina on the dock layout in our chart book to accomodate our best turning radius. As one earlier poster said, he got tired of always having to turn left after fifteen years of doing so. I certainly understand that, but for me a little planning ahead doesn't really bother me, I even kind of enjoy it. I also find having all that extra thrust in reverse allows me to manuever a little more definitively in high winds, ie at a higher speed coming in to the slip because I know I have plenty of braking power, and that when I apply that braking power the boat will move sideways to starboard as it comes to a stop. This is very helpful in high winds as the wind doesnt have time to blow the bow off. My teeny wife is my only line handler. The boat weighs 65,000 lbs. tanks empty and has a pilothouse and high sheer, therefore lots of windage.
I find it simple to go in a straight line astern, despite my pronounced propwalk. I was always taught that when going astern, since every boat has SOME propwalk, you apply a burst of throttle in reverse and then drop it back in neutral. Then another burst or two if needed. Almost like a thruster! I thought everyone did it this way. Just putting the boat in reverse and leaving it there and then expecting it to go in a straight line is silly. On some boats I have been on the propwalk is stronger than the helm at any speed under a knot or two, so the boat won't answer the helm at all with the engine in reverse and will only turn one way. That's why you give it a burst to get steerage way in reverse, and then drop it in neutral. As soon as you drop it in neutral the boat answers the helm again. Underbody certainly has a major effect on steerage in reverse, but regardless of underbody you'll never go in a straight line in reverse if you just put the boat in gear and leave it there.
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Old 27-08-2012, 06:22   #169
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Re: Hmmmm - Bowthrusters ??

You SPECIFY a bow in starboared side blah blah blah ?

In my part of the world you're lucky to get into a marina on short notice and you get what you get.

surely knowing how your boat handles, prop walk and all is essential to docking and any other manouver.

I don't really understand what this discussion is about...as for the guy that has a bow thruster on a 35ft yacht....seriously ??? If you can't dock a 35ft yacht without a bow thruster, you need more practise..or stay on land where life is more predictable
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Old 27-08-2012, 07:54   #170
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Re: Hmmmm - Bowthrusters ??

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We're sailing to Crisfield MD for the watermen's docking competition. Not expecting to see any bow thrusters.
I always like to give the benefit of the doubt - and try to understand the cultural bias from which comments like this are made

So I took the trouble to check out the Crisfield Docking competition and then analysed what i saw against its cultural backdrop

Now i get where all these comments are coming from...

Nope - there wont be any thrusters at Crisfield ( way too sophisticated )

Just really glad i now understand what you guys think is world's best practise docking - it sort of helps me understand all your comments from now on

For everyone else's instructional benefit - check out pics 1, 3 and 17 to see whether these techniques will work in your local marina ,,,,



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Old 27-08-2012, 07:59   #171
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Re: Hmmmm - Bowthrusters ??

Crisfield Maryland News and Photography: 39th annual Boat Docking Contest in Crisfield - 2010
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Old 27-08-2012, 08:03   #172
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Re: Hmmmm - Bowthrusters ??

Minaret,

CAll ahead and specify a landing????????? In Denmark I only know of a couple of harbour where you can even reserve a space - much less one with a starboard landing. Hell, this summer I jockeyed my 40 footer around on the island of bornholm, and the boats were laying 4-5 out on each others sides. The harbours are so small that there basically there isn't enough room to turn a 40 footer. Happy I had a BT.

Worst I've ever seen was 14 boats out fro the pier on the swedish island of Hven 14 boats, you could almost walk dry footer across the harbour on the boats
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Old 27-08-2012, 08:07   #173
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Re: Hmmmm - Bowthrusters ??

Don't think there is any offence taken by your comments regarding whether or not a cruiser should have a thruster or not simply because we all make our own choices viva la difference..
The offence is elsewhere.
Cheers hope the OP has gained some insight here, yes thrusters, amongst other tools, can be of great assistance more so in tight marinas.

Cheers
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Old 27-08-2012, 08:10   #174
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Re: Hmmmm - Bowthrusters ??

I thought only the Superyachts got that treatment, here you are met by a man on a scooter blowing a whistle directing you to an unseen pen or telling you to leave "NOT POSSIBLE" They scream and on you move........
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Old 27-08-2012, 09:07   #175
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Re: Hmmmm - Bowthrusters ??

i think that if bow thrusters are not "de rigeur" then something should be said about the other end of the boat ..as some kind of compensatory gesture

This vessel seems to have at its message under control when it comes to reversing

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Old 27-08-2012, 11:18   #176
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Re: Hmmmm - Bowthrusters ??

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Minaret,

CAll ahead and specify a landing????????? In Denmark I only know of a couple of harbour where you can even reserve a space - much less one with a starboard landing. Hell, this summer I jockeyed my 40 footer around on the island of bornholm, and the boats were laying 4-5 out on each others sides. The harbours are so small that there basically there isn't enough room to turn a 40 footer. Happy I had a BT.

Worst I've ever seen was 14 boats out fro the pier on the swedish island of Hven 14 boats, you could almost walk dry footer across the harbour on the boats

Well, if your "cruising" occurs only in Danish waters, it sounds like you have made a good choice. In most of the world conditions are not so crowded. If you were to go further afield you might find you don't need a thruster anymore. You also might find that better fuel economy is much more appealing than better manueverability.
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Old 27-08-2012, 11:23   #177
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Re: Hmmmm - Bowthrusters ??

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Old 27-08-2012, 20:48   #178
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Tricky to fair in a thruster if 8mm steel. This is a 12" tube for a 30hp hydraulic Sidepower. Loss of interior space not a problem. Maybe slightly increased resistance but i doubt if it will make any measurable difference to this yacht.
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Old 27-08-2012, 20:51   #179
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Old 28-08-2012, 00:08   #180
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Re: Hmmmm - Bowthrusters ??

Nice work, (round bilge?) I have fitted removable plugs on similar installations to cut down on drag but afterwards i wondered was it really worth the effort as quite often water inlets have the same effect, more so when large to accommodate manifolds etc albeit they are not forward.

When sailing or motoring this area is very aerated anyway probably as you say quite negligeable. Cheers Frank

Regards Frank.
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