Cruisers Forum
 


Join CruisersForum Today

Closed Thread
 
Thread Tools Rate Thread Display Modes
Old 26-07-2011, 16:30   #91
Registered User
 
cat man do's Avatar

Join Date: Aug 2006
Location: Brisbane Australia [until the boats launched]
Boat: 50ft powercat, light,long and low powered
Posts: 4,409
Images: 36
Re: How Safe Are Trawlers in Big Seas ?

Quote:
Originally Posted by Astrid View Post
And a catamaran that is a trawler/fishing vessel, as per the definition of "Trawler" used here by some.
Professional Aluminium Fishing Boats. Commercial Catamarans.

Boats for sale South Africa, Used boat sales, Commercial For Sale Aluminium Catamaran Fishing Vessel - Apollo Duck

Geo Shipyard :: Portfolio
__________________

__________________
"Money can't buy you happiness but it can buy you a yacht large enough to pull up right alongside it"...............David Lee Roth
Long Distance Motorboat Cruising – It Is Possible on a Small Budget
cat man do is offline  
Old 26-07-2011, 16:32   #92
Registered User
 
psneeld's Avatar

Join Date: Oct 2010
Location: Avalon, NJ
Boat: Albin 40 double cabin Trawler
Posts: 1,831
Re: How Safe Are Trawlers in Big Seas ?

Quote:
Originally Posted by ChristiGrab View Post
jkleins got my point exactly!

psneeld: Bad fuel creates a catastrophic engine failure. Sucking in a jellyfish or plastic bag creates a catastrophic engine failure. raw sea water rapidly eroding your engine can create a catastrophic engine failure. My point is that you need a complete propulsion system that is designed to prevent the things that create catastrophic engine failures. You are kidding aren't you...NONE of those ever ruined one of my engines...and I've had'em all plus dozens of other boats I've repaired/delivered.

Now to address your comment about it being possible to never be in big seas... if you have an unlimited amount of time to wait for the perfect weather window and no concerns about visa issues, it could be possible. But, in the real world, visas expire and you have to leave even if the weather window isn't ideal. In the real world, where it takes 3 weeks to cross an ocean, the forecast can change in that three weeks. And while forecasting is indeed pretty darn good, more than once we got caught in a storm that was not forecast. When we crossed the Pacific, we had 15 - 20 foot seas virtually every day all the way from San Diego to Australia. It only got worse the farther west we went. And those were the "good" travel days! Several times we got stuck waiting out worse weather!

Again...many cruisers routinely avoid bad weather ...maybe not totally but enough to miss the worst of it.

Oh, and my cousin is a merchant marine. He gets stuck in LOTS of bad weather. They stick to their schedule no matter what.
Merchies DO have to stick to schedules and routes to a point...many lose their lives when they stick to it and shouldn't....
__________________

__________________
psneeld is offline  
Old 26-07-2011, 16:44   #93
Registered User

Join Date: Jul 2010
Location: New Mexico, USA
Boat: International Etchells USA 125 Black Magic, Santana 20 475 Ghost, Hobie 33 3100 Bruja, dinghies,
Posts: 1,118
Re: How Safe Are Trawlers in Big Seas ?

(all ye ancient mariners who already know this can skip over this stuff or just nitpick it for fun)

As my limited brain and limited experience understand the issue:

There are various numbers that purport to have some relationship to the stability of a vessel, and these have probably been talked to death on other threads or forums -- people who know their way around the forums might be able to dig up appropriate links. They generally work better for discussing relatively similar hull forms, such as monohull displacement sailboats.

Very simply, a couple of the simple ones are the Capsize Screening Formula and Angle of Vanishing Stability.

The CSF (in feet, beam/cube root of cubic feet [or lbs. displacement / 64.2]) only looks at displacement and beam and hence overlooks a whole lot of the characteristics that make one boat more stable than another. All it says, really, is that big deep boats won't capsize as often as little flat boats. A CSF below 2 is better than a bigger number.

AVS (or limit of positive stability), as it implies, is the angle beyond which a boat, in calm conditions, won't return to upright. Even in rough seas, a boat with a high AVS, such as 135 degrees or more, will tend to get rolled back upright, whereas a boat that had an AVS of less than 90 would tend to be happy to stay upside down. The AVS formula is a smidge more sophisticated than CSF in that it considers a vessel's draft and proportion of ballast in addition to beam and displacement.

Obviously, these are only beginning approximations to what a real boat would do in the real world, and fall short of many of the issues that naval architects and physicists would consider -- centers of gravity, moments of inertia, effect of weight distribution, chines & various hull form details, roll dampening from sails and spars, interaction of different types of motion, blah, blah, yada yada, etc.

You could get even more sophisticated and real-worldly by subjecting a vessel to a inclination test -- actually measure the response of a boat to being heeled/having weights put on board in different places to learn about the vessel's center of gravity. A naval architect or builder may have also arranged for a "curve of static stability" (GZ) to be drawn for a loaded vessel. And no doubt there are more sophisticated measurements. Now maybe the experts can come in and tell us if they have any numbers that they believe predict something about stability in the real world.
__________________
Pat, from the Desert Sea http://desertsea.blogspot.com
rgscpat is offline  
Old 26-07-2011, 17:34   #94
Moderator Emeritus
 
hummingway's Avatar

Cruisers Forum Supporter

Join Date: Jan 2010
Location: Gabriola Island & Victoria, British Columbia
Boat: Cooper 416 Honeysuckle
Posts: 6,933
Images: 5
Re: How Safe Are Trawlers in Big Seas ?

Quote:
Originally Posted by Astrid View Post
And I thought I had a problem with seagulls crapping on my boat!
__________________
“We are the universe contemplating itself” - Carl Sagan

hummingway is offline  
Old 26-07-2011, 19:07   #95
Registered User
 
markpierce's Avatar

Join Date: Aug 2010
Location: Central California
Boat: M/V Carquinez Coot
Posts: 3,416
Re: How Safe Are Trawlers in Big Seas ?

Quote:
Originally Posted by ChristiGrab View Post
jkleins got my point exactly!

psneeld: Bad fuel creates a catastrophic engine failure. Sucking in a jellyfish or plastic bag creates a catastrophic engine failure. raw sea water rapidly eroding your engine can create a catastrophic engine failure.
A sailboat's engine is more likely to fail than a motorboats since sailors don't pay as much attention.

Recreational trawlers have sophisticated fuel-filter systems:






Proper recreational trawlers have screens to keep junk from being sucked into the engine's cooling system:



Sea-water-cooled diesel engines have zincs to minimize erosion.

A broken mast or torn sails don't affect a motorboat's primary motive source.
__________________
Kar-KEEN-ez Koot
markpierce is offline  
Old 26-07-2011, 19:10   #96
Registered User
 
psneeld's Avatar

Join Date: Oct 2010
Location: Avalon, NJ
Boat: Albin 40 double cabin Trawler
Posts: 1,831
Re: How Safe Are Trawlers in Big Seas ?

Quote:
Originally Posted by rgscpat View Post
(all ye ancient mariners who already know this can skip over this stuff or just nitpick it for fun)

As my limited brain and limited experience understand the issue:

There are various numbers that purport to have some relationship to the stability of a vessel, and these have probably been talked to death on other threads or forums -- people who know their way around the forums might be able to dig up appropriate links. They generally work better for discussing relatively similar hull forms, such as monohull displacement sailboats.

Very simply, a couple of the simple ones are the Capsize Screening Formula and Angle of Vanishing Stability.

The CSF (in feet, beam/cube root of cubic feet [or lbs. displacement / 64.2]) only looks at displacement and beam and hence overlooks a whole lot of the characteristics that make one boat more stable than another. All it says, really, is that big deep boats won't capsize as often as little flat boats. A CSF below 2 is better than a bigger number.

AVS (or limit of positive stability), as it implies, is the angle beyond which a boat, in calm conditions, won't return to upright. Even in rough seas, a boat with a high AVS, such as 135 degrees or more, will tend to get rolled back upright, whereas a boat that had an AVS of less than 90 would tend to be happy to stay upside down. The AVS formula is a smidge more sophisticated than CSF in that it considers a vessel's draft and proportion of ballast in addition to beam and displacement.

Obviously, these are only beginning approximations to what a real boat would do in the real world, and fall short of many of the issues that naval architects and physicists would consider -- centers of gravity, moments of inertia, effect of weight distribution, chines & various hull form details, roll dampening from sails and spars, interaction of different types of motion, blah, blah, yada yada, etc.

You could get even more sophisticated and real-worldly by subjecting a vessel to a inclination test -- actually measure the response of a boat to being heeled/having weights put on board in different places to learn about the vessel's center of gravity. A naval architect or builder may have also arranged for a "curve of static stability" (GZ) to be drawn for a loaded vessel. And no doubt there are more sophisticated measurements. Now maybe the experts can come in and tell us if they have any numbers that they believe predict something about stability in the real world.
Like many fishing boats that have capsized and sunk...it wasn't the design that did it...

It was operator error plus improper loading and often some free surface effect thrown in.

Theory is where you start but it's what the cruiser does or doesn't do that is just as dangerous in terms of stability.
__________________
psneeld is offline  
Old 26-07-2011, 19:11   #97
Moderator Emeritus
 
hummingway's Avatar

Cruisers Forum Supporter

Join Date: Jan 2010
Location: Gabriola Island & Victoria, British Columbia
Boat: Cooper 416 Honeysuckle
Posts: 6,933
Images: 5
Re: How Safe Are Trawlers in Big Seas ?

Does all this sail/motor is more likely to break then motor/sail seem a little poorly thought out to anyone other then me? I'm hoping you all have your tongues firmly planted in your cheeks and have forgot we have emoticons.
__________________
“We are the universe contemplating itself” - Carl Sagan

hummingway is offline  
Old 26-07-2011, 19:14   #98
Registered User
 
psneeld's Avatar

Join Date: Oct 2010
Location: Avalon, NJ
Boat: Albin 40 double cabin Trawler
Posts: 1,831
Re: How Safe Are Trawlers in Big Seas ?

Quote:
Originally Posted by markpierce View Post
A sailboat's engine is more likely to fail than a motorboats since sailors don't pay as much attention.
Thank you...nice response!

But I'll standby what I was inferring before....even the most neanderthal engine setup doesn't catastrophically fail for common reasons...usually it's long term neglect, old age, or factory defect...unless it's operator error from the git go....
__________________
psneeld is offline  
Old 26-07-2011, 19:24   #99
Senior Cruiser
 
Blue Stocking's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: St. Georges, Bda
Boat: Rhodes Reliant 41ft
Posts: 4,117
Re: How Safe Are Trawlers in Big Seas ?

Quote:
Originally Posted by hummingway View Post
Does all this sail/motor is more likely to break then motor/sail seem a little poorly thought out to anyone other then me? I'm hoping you all have your tongues firmly planted in your cheeks and have forgot we have emoticons.
Mark,

Don't let me down now- I complemented you earlier in this forum
But that last post has me agreeing with Hummingway.
Sailing vessels may not have as fancy a filtration set-up as yours because the engine is generally is considered the 2nd line power source.
But I have also worked in sailboat engine rooms with far more sophicated filtration and lube systems than you show.
__________________
so many projects--so little time !!
Blue Stocking is online now  
Old 26-07-2011, 19:30   #100
Registered User
 
ChristiGrab's Avatar

Join Date: Dec 2010
Location: San Diego
Boat: Nordhavn 43
Posts: 40
Re: How Safe Are Trawlers in Big Seas ?

Quote:
In the real world, wouldn't you leave your boat in a marina and hop over the border into another country , get stamped, come back in and then leave on the boat when weather is more favourable? In the real world, can you be forced out into unfavourable weather conditions or are the powers that be more likely to give you an extension until the weather clears?
Obviously, you have limited foreign cruising experience. Nope, it is not always that easy. You'll be very interested in a story in my upcoming book about three boats having to leave Indonesia in bad weather due to expired visas--2 sailboats and us. One dismasted and had to return; they were allowed in. The other returned because the conditions were so unsafe. They were immediately arrested. The other boat was us. We pounded through and made it safely, but it was AWFUL.

Quote:
You are kidding aren't you...NONE of those ever ruined one of my engines...and I've had'em all plus dozens of other boats I've repaired/delivered.
What would you do if you had 2,000 miles to the nearest port and bad fuel shut down your engine and you had no steering control? I stand by my statement that all the weakness I mentioned have the POTENTIAL to be catastrophic. They won't necessarily be, but why take the chance? Start with a system that is robust to start with.
__________________
ChristiGrab is offline  
Old 26-07-2011, 19:31   #101
Registered User
 
Capt Phil's Avatar

Join Date: Jun 2010
Location: Stateline NV
Boat: Prior boats: Transpac 49; DeFever 54
Posts: 2,749
Re: How Safe Are Trawlers in Big Seas ?

Hummingway, you got me LMAO again! On a more sincere note, it is a pity that sea chests have gone out of vogue... easy to clean, spot trouble and good protection for salt water cooled power plants. Best of all worlds is dry exhaust/keel coolers IMHO.
Fuel needs to be stored low, multiple filters/polishing systems and redundant transfer and pumping capabilities as well as the ability to examine fuel BEFORE being pumped aboard from questionable sources. Nice to have a get home for single engined boats as well. Capt Phil
__________________
Capt Phil is offline  
Old 26-07-2011, 19:35   #102
Registered User
 
psneeld's Avatar

Join Date: Oct 2010
Location: Avalon, NJ
Boat: Albin 40 double cabin Trawler
Posts: 1,831
Re: How Safe Are Trawlers in Big Seas ?

Quote:
Originally Posted by ChristiGrab View Post
Obviously, you have limited foreign cruising experience. Nope, it is not always that easy. You'll be very interested in a story in my upcoming book about three boats having to leave Indonesia in bad weather due to expired visas--2 sailboats and us. One dismasted and had to return; they were allowed in. The other returned because the conditions were so unsafe. They were immediately arrested. The other boat was us. We pounded through and made it safely, but it was AWFUL.


What would you do if you had 2,000 miles to the nearest port and bad fuel shut down your engine and you had no steering control? I stand by my statement that all the weakness I mentioned have the POTENTIAL to be catastrophic. They won't necessarily be, but why take the chance? Start with a system that is robust to start with.
I guess LIKE the weather...know before you go...

I know some countries just can't be dealt with but force majure has worked plenty of times for others...tough straightening out but better than dying...

Guess I inspect my fuel better....
__________________
psneeld is offline  
Old 26-07-2011, 19:37   #103
Registered User
 
markpierce's Avatar

Join Date: Aug 2010
Location: Central California
Boat: M/V Carquinez Coot
Posts: 3,416
Re: How Safe Are Trawlers in Big Seas ?

Quote:
Originally Posted by Blue Stocking View Post
But I have also worked in sailboat engine rooms with far more sophicated filtration and lube systems than you show.
I didn't show my fuel-polishing system because they aren't typically installed.
__________________
Kar-KEEN-ez Koot
markpierce is offline  
Old 26-07-2011, 19:39   #104
Registered User
 
cat man do's Avatar

Join Date: Aug 2006
Location: Brisbane Australia [until the boats launched]
Boat: 50ft powercat, light,long and low powered
Posts: 4,409
Images: 36
Re: How Safe Are Trawlers in Big Seas ?

Quote:
Originally Posted by ChristiGrab View Post
Obviously, you have limited foreign cruising experience. Nope, it is not always that easy. You'll be very interested in a story in my upcoming book about three boats having to leave Indonesia in bad weather due to expired visas--2 sailboats and us.
So thats one place
Across the ditch in Malaysia I know people who have been there for years and do exactly what I said.
Google Visa runs
__________________
"Money can't buy you happiness but it can buy you a yacht large enough to pull up right alongside it"...............David Lee Roth
Long Distance Motorboat Cruising – It Is Possible on a Small Budget
cat man do is offline  
Old 26-07-2011, 19:43   #105
Registered User
 
psneeld's Avatar

Join Date: Oct 2010
Location: Avalon, NJ
Boat: Albin 40 double cabin Trawler
Posts: 1,831
Re: How Safe Are Trawlers in Big Seas ?

Quote:
Originally Posted by ChristiGrab View Post
Obviously, you have limited foreign cruising experience. Nope, it is not always that easy. You'll be very interested in a story in my upcoming book about three boats having to leave Indonesia in bad weather due to expired visas--2 sailboats and us. One dismasted and had to return; they were allowed in. The other returned because the conditions were so unsafe. They were immediately arrested. The other boat was us. We pounded through and made it safely, but it was AWFUL.


What would you do if you had 2,000 miles to the nearest port and bad fuel shut down your engine and you had no steering control? I stand by my statement that all the weakness I mentioned have the POTENTIAL to be catastrophic. They won't necessarily be, but why take the chance? Start with a system that is robust to start with.
Geez...I crammed my boating, cruising and pole to pole voyaging with the USCG into a measly 50 years.....
__________________

__________________
psneeld is offline  
Closed Thread

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
Calculating Safe Depth - Bar Crossing Dockhead Seamanship & Boat Handling 15 14-07-2011 14:37



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 10:01.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.