direct drive - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 


Like Tree4Likes
Reply
 
LinkBack Thread Tools
  #1  
Old 12-14-2013
Member
 
Join Date: Feb 2012
Location: PNW
Posts: 43
Thanks: 5
Thanked 1 Time in 1 Post
Rep Power: 0
jraymer is on a distinguished road
direct drive

Hi everybody;

I'm boat shopping and was looking at a 2001 jeanneau so 37 that said the shaft is direct drive.
I'm wondering if there are transmissions or drives that I should be careful with?
Does direct drive mean the prop turns at the same speed as the engine?
Thanks for any info.

Jim.
Reply With Quote Quick reply to this message Share with Facebook
  #2  
Old 12-14-2013
CalebD's Avatar
Tartan 27' owner
 
Join Date: Jan 2008
Location: NYC
Posts: 4,616
Thanks: 4
Thanked 92 Times in 85 Posts
Rep Power: 7
CalebD will become famous soon enough
Re: direct drive

Quote:
Originally Posted by jraymer View Post
Does direct drive mean the prop turns at the same speed as the engine?
Yes. 1:1.

On larger, heavier boats it is more common to find a reduction gear of, say 2.x:1. With the reduction gear a larger prop can be spun giving more thrust.

That said, there is nothing wrong with direct drive transmissions if the prop can be sized to efficiently move the boat with some power left over for when needed. You would need to do a sea trial under power to asses how the drive train performs.
__________________
"The cure for anything is salt water~ sweat, tears, or the sea." ~Isak Denesen

Everybody has one:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message Share with Facebook
  #3  
Old 12-14-2013
jrd22's Avatar
Courtney the Dancer
 
Join Date: Nov 2000
Location: San Juan Islands., WA, USA
Posts: 3,843
Thanks: 3
Thanked 16 Times in 16 Posts
Rep Power: 15
jrd22 will become famous soon enough
Re: direct drive

I'd be surprised on that new of a boat that it is truly a direct drive (on older boats direct drive meant no transmission at all, you shut the engine down, pulled a lever that moved the camshaft and then started the engine again, rotating the opposite direction). I would guess they are just meaning there is no V-drive, but you never know.
Faster and mitiempo like this.
__________________
John
SV Laurie Anne

1988 Brewer 40 Pilothouse

Reply With Quote Quick reply to this message Share with Facebook
  #4  
Old 12-14-2013
Senior Member
 
Join Date: Dec 2003
Posts: 1,388
Thanks: 1
Thanked 18 Times in 17 Posts
Rep Power: 12
capttb is on a distinguished road
Direct drive is sometimes used to denote a conventional drive as opposed to saildrive.
__________________
"Just call me TB"
Reply With Quote Quick reply to this message Share with Facebook
  #5  
Old 12-15-2013
boatpoker's Avatar
Senior Member
 
Join Date: Jul 2008
Location: Toronto
Posts: 1,083
Thanks: 8
Thanked 25 Times in 24 Posts
Rep Power: 7
boatpoker is on a distinguished road
Re: direct drive

Quote:
Originally Posted by jrd22 View Post
I'd be surprised on that new of a boat that it is truly a direct drive (on older boats direct drive meant no transmission at all, you shut the engine down, pulled a lever that moved the camshaft and then started the engine again, rotating the opposite direction). I would guess they are just meaning there is no V-drive, but you never know.
jrd22 has it right and that model does not have a direct drive. You can't always trust that the broker who wrote the ad' actually knows what he is talking about.
__________________
Dirt People Scare me
Reply With Quote Quick reply to this message Share with Facebook
  #6  
Old 12-15-2013
Geoff54's Avatar
Senior Member
 
Join Date: Oct 2011
Posts: 699
Thanks: 1
Thanked 7 Times in 7 Posts
Rep Power: 4
Geoff54 is on a distinguished road
Re: direct drive

Quote:
Originally Posted by boatpoker View Post
jrd22 has it right and that model does not have a direct drive. You can't always trust that the broker who wrote the ad' actually knows what he is talking about.
Sorry to disagree with you ( again ) but in this case I think the broker who wrote the ad' actually does know what he is talking about.

I was pretty sure but I checked, just in case....



__________________
"The great thing about the internet is that you can quote anyone and no one will bother to check the source" - Aristotle
Reply With Quote Quick reply to this message Share with Facebook
  #7  
Old 12-15-2013
boatpoker's Avatar
Senior Member
 
Join Date: Jul 2008
Location: Toronto
Posts: 1,083
Thanks: 8
Thanked 25 Times in 24 Posts
Rep Power: 7
boatpoker is on a distinguished road
Re: direct drive

[quote=Geoff54;1220378]Sorry to disagree with you ( again ) but in this case I think the broker who wrote the ad' actually does know what he is talking about.

Sorry, I don't understand what you mean. Your diagram clearly shows a gear reduction unit and all your photo shows is a shaft drive which does not mean it is a direct drive.

"direct drive" is a very specific type of drive without a gear reduction unit. No production pleasure craft is built that way. For more information on what is is, try here Tugboat Society of America
__________________
Dirt People Scare me

Last edited by boatpoker; 12-15-2013 at 06:49 AM.
Reply With Quote Quick reply to this message Share with Facebook
  #8  
Old 12-15-2013
Member
 
Join Date: Feb 2012
Location: PNW
Posts: 43
Thanks: 5
Thanked 1 Time in 1 Post
Rep Power: 0
jraymer is on a distinguished road
Re: direct drive

Quote:
Sorry, I don't understand what you mean. Your diagram clearly shows a gear reduction unit and all your photo shows is a shaft drive which does not mean it is a direct drive.
Thanks all, I think I get it. So how about more info on saildrives and v-drives.

Jim

Last edited by Faster; 12-15-2013 at 01:59 PM. Reason: fixed quote
Reply With Quote Quick reply to this message Share with Facebook
  #9  
Old 12-15-2013
mitiempo's Avatar
Senior Member
 
Join Date: Sep 2008
Location: Victoria B.C. Canada
Posts: 7,282
Thanks: 0
Thanked 79 Times in 70 Posts
Rep Power: 8
mitiempo will become famous soon enough mitiempo will become famous soon enough
Re: direct drive

V-Drives often make it hard to service the engine as the service points - waterpump, alternator, etc - are hard to reach/

Saildrives are basically like the lower drive unit of an outboard coupled to an engine mounted inside the boat. Lots of aluminum in the water and if strict maintenance is not adhered to there can be serious corrosion problems. Easy for the builder though.

Conventional shaft drive like the diagram above is the simplest most reliable system.
jraymer likes this.
__________________
Brian
Living aboard in Victoria Harbour
Reply With Quote Quick reply to this message Share with Facebook
  #10  
Old 12-15-2013
Faster's Avatar
Just another Moderator
 
Join Date: Sep 2005
Location: New Westminster, BC
Posts: 15,312
Thanks: 88
Thanked 241 Times in 232 Posts
Rep Power: 10
Faster has a spectacular aura about Faster has a spectacular aura about Faster has a spectacular aura about
Re: direct drive

Here's a V drive transmission:



Ignore the arrow in the right hand image, intended for another discussion.

The engine sits 'backwards' in the boat, the gearbox at the forward end, and the shaft exits the V drive under the engine.. Many such installs put the stuffing box and its gland/seal directly under the oil pan in an almost impossible-to-access place. A most compelling reason to install a dripless seal, as a spraying leaky gland can do nothing good for the pan.
jrd22 likes this.
__________________
Ron

1984 Fast/Nicholson 345 "FastForward"

".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
Reply With Quote Quick reply to this message Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Catalina Direct SpeedAgent Gear & Maintenance 29 01-09-2014 06:15 PM
North Sails Direct? MauiPunter Gear & Maintenance 2 11-23-2013 01:37 PM
Key West to Bimini (Direct)? creedence623 General Discussion (sailing related) 30 06-20-2012 12:18 AM
Direct TV Minnewaska Gear & Maintenance 8 12-20-2010 08:58 PM


All times are GMT -4. The time now is 12:50 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.