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Old 01-19-2012, 07:50 PM   #81
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RE: Backing

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Woodsong wrote:Egregious wrote:
Here's my GPS track entering and exiting Eau Gallie Yacht basin.* This was the tightest fit we've ever had to try.* Had to back in since the fingers were fixed and about 5 feet long, and we wouldn't have been able to get on or off the boat!

At home I try to back in or at least leave her backed in before I go home since the rude boaters*don't seem to slow down, and I'd rather get waked from the bow.

On a transient dock I do whatever makes it easiest to exit the next day (usually backing in) or if no current or wind I consider where the shore power pylon is located -- I prefer to park so that the pylon is close to the shore power hookup on my starboard bow.*
*

I was going to humbly admit you are more man than me b/c no way I would want to back my Monk in reverse down that lane, current or not...but then...then I remembered you have twin engines!!! * That's like cheating!

*

single screw= we go bow in.

twin screw= stern first.



-- Edited by Woodsong on Thursday 19th of January 2012 03:25:12 PM

*Woodsong,

After a two month cruise I was totally against twins.* Repairs in Charleston and then again in New Smyrna Beach helped convince me that twice the motors = twice the maintenance.* I hated having two motors!

HOWEVER.** getting into and out of a slip is awesome with twins and is almost worth the extra time and money.** I will consider all of this when I purchase my next boat.

The jury is still out.* At least for me.* I had guys approach me on the dock after I got tied up who told me how good a job I did.* And I just said "I got twins so it was easy."

However, I also saw some sailboats do it better than I did, all relaxed and backing in, and they made me look silly.* I'd say if you can back a sailboat into a slip then you can back anything in.
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Old 01-19-2012, 07:54 PM   #82
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RE: Backing

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rwidman wrote:
On the rare occasions when someone docks one of the larger boats bow in (usually to be worked on), the anchor ends up hanging over the dock as a hazzard to people on the dock.

Of course, you're supposed to watch where you are walking so nobody says anything.
*Ron, we had one on our dock sometime back that so many people had banged their heads on the anchor that someone taped foam rubber over it.
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Old 01-19-2012, 08:30 PM   #83
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Backing

Quote:
Egregious wrote:
*Woodsong,

After a two month cruise I was totally against twins.* Repairs in Charleston and then again in New Smyrna Beach helped convince me that twice the motors = twice the maintenance.* I hated having two motors!

HOWEVER.** getting into and out of a slip is awesome with twins and is almost worth the extra time and money.** I will consider all of this when I purchase my next boat.

The jury is still out.* At least for me.* I had guys approach me on the dock after I got tied up who told me how good a job I did.* And I just said "I got twins so it was easy."

However, I also saw some sailboats do it better than I did, all relaxed and backing in, and they made me look silly.* I'd say if you can back a sailboat into a slip then you can back anything in.
*

I hear you on the cost of twins! *All my previous boats to our Monk were twins and the pilothouse we just bought happens to have twins. *I am having the marina the boat is at right now do full service on both engines and generator right now due to distance from me and lack of time to do it myself before we leave on our 275 mile delivery home trip next week. *I am going to have to tell the service yard that their bill is "TWICE what I pay for my trawler and clearly you have overbilled me!" *haha.

The handling of twins is great, the cost, not as so great. *It is a give and take but seriously- I personally would not want to try and back my Monk into the fairway you posted with just a single. *Someone else could do it perhaps but I am not so sure I could. *I guess if I had to perhaps but I've never tried backing down my Monk that far of a distance before so it would certainly be an unknown! *But ah...with twins....not a problem!


-- Edited by Woodsong on Thursday 19th of January 2012 09:30:48 PM
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Old 01-19-2012, 09:13 PM   #84
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RE: Backing

Hey Woodsong,I hope you have faith in the mechanics and the marina to embark on a journey in a new boat.Well,something tells me that you are right on top of the situation.have a safe trip,and also have a fun trip.GOOD LUCK!
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Old 01-20-2012, 03:28 PM   #85
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RE: Backing

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Moonstruck wrote:skipperdude wrote:Pineapple Girl wrote:* We fit completely within our slip.*
*So your slip isn't showing then.

SD

*Dude, i think that went over their heads.

*I just saw it!* Silly Dude.*
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Old 10-06-2014, 08:04 PM   #86
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1976 Grand Banks twin props

I'm a sailor going from an auxiliary sailboat with a single prop to a trawler, either single prop or twin prop.

I'm looking at a 1976 Grand Banks 36' with twin John Deere's, 107 HP each. The port propeller is 24" x 21" and the starboard propeller is 24" x 18.5".

First, which is the correct pitch: 21" or 18.5" ?

Second, is there something rational to this difference in propeller pitch -- such as correcting steering torque?

Or is it something as simple as the owner having to replace a prop, and he installed the only one he had, which was a different pitch from the other one?

Thx!

JC
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Old 10-06-2014, 08:18 PM   #87
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Are both gearbox ratios the same?
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Old 10-06-2014, 08:57 PM   #88
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Originally Posted by jwchessell View Post
Second, is there something rational to this difference in propeller pitch...


JC
Yes. We have a twin engine GB36, one of the first fiberglass GBs made. It has a pair of FL120s and BW Velvet Drive transmissions.

Twin engine boats usually have counter-rotating propellers. In some instances, the engines actually rotate opposite directions. But in most cases, the engines both rotate the same way and one of the props is rotated the opposite direction by its transmission.

Most twins have the starboard prop rotating clockwise (as seen from the rear of the boat) and the port prop rotating counterclockwise. The engines, at least the FL120 and probably most engines, rotate counterclockwise.

So our starboard transmission has an extra gear in it to make the startboard prop turn clockwise.

BUT.... fitting an extra gear into the transmission changes the final drive ratio a little bit because of the sizing limitations imposed by the transmission's case.

So even though both engines are going the same rpm at cruise (1650 in our case) the props are not going the same rpm. So to get the same thrust from both props, the slower turning prop is given more pitch.

On our boat as delivered in 1973, one prop had a pitch of 18" and the other one had a pitch of 17." The prop with the 18" pitch had the slower rpm when the engines were going the same rpm.

The original three-bladed props on our boat were changed to four-bladed props by a previous owner. They were supposed to have the same 18" and 17" pitches of the original props, but they didn't. Long story short, when we had the props totally reworked a number of years ago, the prop shop said that they had found having the pitches different between port and starboard really didn't make any difference with a GB36 like ours, and they recommended pitching both sides the same.

Which is what we had them do. They are now both 16" pitch because they're four-bladed instead of three-bladed. One blade still goes slower than the other one at the same engine rpm, but the shop is right--- we don't notice a lick of difference in steering or the directional characteristics of our boat with the slightly different thrust between port and starboard.

But if you have questionss about the props on the boat your interested in, I would strongly suggest you talk to an experienced and reputable prop shop. Information they asked us to provide when we decided to have our props worked over were:

What is the make and model of our boat?
What is the wide-open-throttle rpm (in gear with the boat moving) of each engine?
What kind of engines and transmissions are in our boat?
What is the horsepower rating of our engines?
And finally, they wanted to see the props currently on the boat.

This last obviously had to be complied with by having the boat hauled, but we had it out of the water for other things plus a bottom job so we simply had the props pulled and took them to the shop.

Bottom line--- there may be good reason why the props on the GB you're interested in have the prop diameters and pitches that they have. Don't automatically assume that because the pitches are different, this indicates a problem.
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