Reply
 
Thread Tools Display Modes
 
Old 05-24-2016, 08:56 PM   #41
Guru
 
refugio's Avatar
 
City: Meydenbauer Bay Yacht Club
Country: USA
Vessel Name: Refugio
Join Date: Mar 2012
Posts: 1,141
Quote:
Originally Posted by Tingum View Post
On another note, is the ram mounted on a piece of star board? If so that is not strong enough.
Yeah it looks like 1/2" with a few 1/4" screws/bolts. That stuff deforms over time but it appears it was a standard GB practice.


Keith
__________________
Advertisement

__________________
Keith
refugio is offline   Reply With Quote
Old 05-24-2016, 10:37 PM   #42
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,913
The stress put on it is directional.....ever hit the edge of a pane of glass? Pretty dang strong.

Run the numbers on strength and what is required and yep....probably worked fine for years because it is strong enough.
__________________

psneeld is offline   Reply With Quote
Old 05-25-2016, 10:32 PM   #43
Guru
 
Northern Spy's Avatar
 
City: Powell River, BC
Country: Canada
Vessel Name: Northern Spy
Vessel Model: Nordic Tug 26
Join Date: Feb 2012
Posts: 2,668
Quote:
Originally Posted by refugio View Post
Are you implying that a smaller area somehow changes the pressure (expressed as force over area)?

And what makes you believe that pressure does not go to 1000 psi? That's the pressure specified by SeaStar for bleeding their system - it's not possible to commission a system that won't hold that pressure. Are you thinking that because most of the time the system isn't pressurized that somehow an average pressure becomes relevant?

Also, note that 1000psi is "minimum operating pressure" for Capilano/Teleflex/SeaStar hydraulic hose. The "burst pressure" is 5000psi.
Fittings typically don't have proportionally thinner wall as the diameter decreases. So as the mean diameter decreases, so does the hoop stress generated by internal pressure. You will often see small diameter fittings with a much higher rating than larger diameter fittings.

Yes you can generate high pressure by cranking the helm into the rudder stops, but normal operating pressure of the helm is a fraction of the tested pressure. Most systems have have reliefs at 900-1000 psi to prevent seal damage.

SAE 100R hose was the typical hose used before vendors came up with specialized hose.

I too like isolation valves, but they can be a curse, as they are often just another leak point later. I would want a cylinder bypass valve for bleeding, and emergency rudder control though.

I know nothing about starboard. Never used the stuff.
Northern Spy is offline   Reply With Quote
Old 05-26-2016, 12:24 AM   #44
Guru
 
Capt.Bill11's Avatar
 
City: Sarasota/Ft. Lauderdale
Country: USA
Join Date: Apr 2014
Posts: 5,422
Quote:
Originally Posted by psneeld View Post
The stress put on it is directional.....ever hit the edge of a pane of glass? Pretty dang strong.

Run the numbers on strength and what is required and yep....probably worked fine for years because it is strong enough.
I don't think you're getting it, the whole system is about to explode any minute now.
__________________

Capt.Bill11 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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





All times are GMT -5. The time now is 12:36 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012