Cruisers Forum

Join CruisersForum Today

Thread Tools Rate Thread Display Modes
Old 12-03-2014, 15:36   #106
Registered User

Join Date: Nov 2012
Posts: 16
Re: Saildrives?

Originally Posted by georgetheleo View Post
It may sound silly but Im afraid of and irrationally opposed to saildrives. Bascally all I really know of them is: the larger Yamaha ones develope slipping "cones" and need special tools and big bucks to repair.what if you are in timbucktooo? The smaller Yamahas dont have this problem but are limited to 30hp. The Volvo saildrives are much more reliable but the volvo engines are not and parts cost a fortune. Why cant saildrives be converted to straight shat drives if there is room? What about those Beta saildrives and engines? Comments please--- Thank You
I agree with you. I had a Belize cat with the Yanmar SD50 and had lots of trouble cost me shed loads of money to get them replaced. We are looking at an Isara 45 catamaran which has shaft drives and mid engine. A lot less hassle.
I would not buy a cat with sail drives again. .

catsrule is offline   Reply With Quote
Old 12-03-2014, 16:39   #107
Registered User
Cotemar's Avatar

Join Date: Dec 2007
Posts: 4,816
Re: Saildrives?

Originally Posted by catsrule View Post
I would not buy a cat with sail drives again. .
Sort of like saying that you wouldn't buy another car because you had one with a bad engine. 99.9999% of all production boats have sail drives that work perfectly.

All those defective Yanmar SD 50 with bad cone clutches should have been recalled by Yanmar. It's clearly a scare on there reputation to sell defective sail drives and not recall and repair them. Shame on them.

Cotemar is offline   Reply With Quote
Old 12-03-2014, 16:41   #108
Registered User

Join Date: Mar 2009
Location: Southern Chesapeake Bay
Boat: Norseman 430, Jabberwock
Posts: 610
Re: Saildrives?

Andrew, looks like you have given this a good study. I haven't looked through your numbers carefully, but assume they are correct.

I wondered about the CoE of oil, but never went to the trouble of finding it. My theory was just speculation, and whether it was fact or not would have no bearing on anything I might do about the saildrive. I was already developing the idea of the expansion tank to relieve pressure differentials from any cause.

But one thing I think your analysis of a simple shape might miss is that the housing is not a uniform shape. The key thing is that the area of the top surface of the oil is small, if the picture in my mind of the upper leg is correct, as compared to the rest of the oil "vessel". Sort of like (but not so extreme) the magnified rise and fall of the liquid in a glass thermometer.

Originally Posted by Andrew Troup View Post
This is my second attempt at this post.

When I pressed "Submit", the forum software evidently thought I was intending to surrender, and decided I wasn't logged on, and tossed my first submission out the air-lock into cyberspace.

(... even though I had just logged back in after the site came back after a maintenance period, and my name appeared at the top of the same page)


I did a quick calc to make sure my intuition here was not off-beam.

Conveniently, because the coeff for alu is double that for steel, and the latter similar to oil, I was able to do the calc for a steel sternleg containing a fluid with a zero coefficient. The answer should be about the same.

(Alu: 20 millionths linear expansion per deg C; Steel and Oil: 10 millionths)

The volume of a 100mm cubic (1 litre) steel container, for 1 deg C increase, would grow to about 1.00001^3 of the original size, or ~ 1.00003
Hence a volumetric increase of 1.00003 1 , or 0.00003 litres

so for a 30 degree C rise, the volumetric increase would be thirty times this, or 0.0009 litres, say 0.001 litres, or one-thousandth of a litre

Which would *roughly* be a level change of one tenth of a millimetre in the original container. (because 100mm level change corresponds to a whole litre)

in US customary units: a change in level of about four one-thousandths of an inch, for a temperature change of about 85 degrees F.
ggray is online now   Reply With Quote
Old 12-03-2014, 16:52   #109
Registered User

Join Date: Nov 2007
Location: galveston tx.
Boat: Searunner 38 catamaran
Posts: 2,817
Re: Saildrives?

I wouldn't let saildrives stop me from buying a cat I really wanted, but I would much rather have straight shaft. Saildrives to me just don't make sense.

Sent from my iPad using Tapatalk
smj is offline   Reply With Quote
Old 12-03-2014, 22:03   #110

Join Date: May 2007
Location: Brisbane AUS
Boat: Cowther 43 - Hunter 40.5
Posts: 1,006
Re: Saildrives?

I'd rather a light cat that sails very well and use outboards.

dennisail is offline   Reply With Quote

Thread Tools
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
Volvo Saildrives - Type of Oil? Cruisin Cat Propellers & Drive Systems 17 25-02-2014 19:22
For Sale: Yanmar Saildrives felix11 Classifieds Archive 6 21-12-2012 13:47
Want To Buy: $500.00 !! REWARD !! For Catamaran Under $120k amphibious1 Classifieds Archive 106 20-09-2012 09:50
Looking for Used SD40 Saildrives Primacat Engines and Propulsion Systems 7 18-10-2011 14:12

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 18:13.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.