Cruisers Forum
 


Join CruisersForum Today

Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 31-07-2019, 17:19   #16
smj
Registered User

Join Date: Nov 2007
Boat: Searunner 38 catamaran
Posts: 4,365
Re: What angle of attack for outboard motors

Quote:
Originally Posted by snoozy814 View Post
ok forgive me for sounding dumb but not my area of expertise. we're looking at repowering either with an IO drive or two outboards and trying to get idea how it worked for others w/their cats. We only have one engine central in the boat w/hydraulic drives now which don't work right. As we're re-designing looking for ideas and input from those who have gone this way. Boat is a 39' Kelsall one off, as of now just a drop centerboard in middle, not on the twin hulls.


Have you considered going with a single outboard? If you’re able to hook the outboard up to the steering system then the maneuverability should be almost as good as twin outboards.
Yamaha just put out a new lightweight 25 hp high thrust with 25” shaft . Would probably work well for you.
__________________

smj is online now   Reply With Quote
Old 31-07-2019, 18:57   #17
Registered User

Join Date: Apr 2013
Posts: 6,927
Re: What angle of attack for outboard motors

Quote:
Originally Posted by smj View Post
Have you considered going with a single outboard? If you’re able to hook the outboard up to the steering system then the maneuverability should be almost as good as twin outboards.
Yamaha just put out a new lightweight 25 hp high thrust with 25” shaft . Would probably work well for you.
That's how our Gemini was set up. Twins are slightly better but not by much. You do need to get used to it as the propwash doesn't doesn't pass over the rudders so if until you get used to it, you have to pay attention to STW vs the steering effect of the rudders. If you are making way, the rudders will override the vectored thrust of the outboard. If you are near stationary, the vectored thrust can be used to spin the boat in place. It works fine but it's different from traditional inboards with propwash over the rudder, so the first few times, you will probably mess up.

An even better improvement is some of put a small lever by he helm to steer the outboard independent of the rudders. This way while the rudders are still in control, you can use the vectored thrust to add to it.

My preference is outboard. Modern fuel injected outboards are quiet and efficient. They also aren't subject to the same gumming up that you get with carburated engines. You can pull the engine completely clear of the water reducing corrosion and growth issues. Gasoline concerns are addressed by putting the tank on the bridge deck and bottom venting them to water (similar to why people don't panic about driving gasoline cars).

I/O units leave the drive in the water all the time so aren't well suited to a cruising boat that stays in a slip full time. There is a special I/O (stillete) that is extra long and can be mounted on the bridge deck but it's a very old design and requires a lot of maintenance to keep operational.
__________________

valhalla360 is offline   Reply With Quote
Old 31-07-2019, 19:34   #18
Senior Cruiser
 
44'cruisingcat's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 9,084
Images: 69
Re: What angle of attack for outboard motors

Quote:
Originally Posted by snoozy814 View Post
ok forgive me for sounding dumb but not my area of expertise. we're looking at repowering either with an IO drive or two outboards and trying to get idea how it worked for others w/their cats. We only have one engine central in the boat w/hydraulic drives now which don't work right. As we're re-designing looking for ideas and input from those who have gone this way. Boat is a 39' Kelsall one off, as of now just a drop centerboard in middle, not on the twin hulls.
A single motor will be lighter, obviously cheaper, and less work to install.

Having said that, two motors is preferable. At sea, the propellers will be better immersed more of the time. Manoeuvring will be easier. And there's the redundancy.

But the motors need to mounted well forward, not hung on the transoms.
__________________

__________________
"You CANNOT be serious!"


John McEnroe
44'cruisingcat is offline   Reply With Quote
Reply

Tags
motor, outboard

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Cheap Outboard Motors nhschneider Auxiliary Equipment & Dinghy 3 08-02-2014 06:17
Tiller Steering and Outboard Motors decca Multihull Sailboats 60 04-07-2013 23:37
9.9/15-hp 4-Stroke Outboard Motors? ranger42c Auxiliary Equipment & Dinghy 56 08-06-2013 15:39
Outboard Motors rourkeh Auxiliary Equipment & Dinghy 11 09-10-2010 12:21
Dinghy Outboard Motors Strygaldwir Engines and Propulsion Systems 16 14-03-2010 08:09

Advertise Here


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 18:11.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
×

ShowCase vBulletin Plugins by Drive Thru Online, Inc.