Reply
 
Thread Tools Display Modes
 
Old 05-08-2013, 08:43 PM   #1
Veteran Member
 
City: Fort McAllister, Ga
Country: Us
Vessel Name: Hot Shot
Vessel Model: Mainship 390
Join Date: May 2012
Posts: 95
Trawler vs Motor Yacht Running Gear

I have talked to some Sea Ray and Carver owners that love their boats because they can go slow for economy, but have the option of going fast if needed. Its an appealing argument.
But when i look at their type of boat out of the water, I see v hulls with small rudders and extremly exposed drive shafts and props. ( I guess so they can go fast) My first thought when i see this is whats going to happen with a hard grounding or hitting a submerged object at speed? Seems to me you could take out the whole damn thing with bent shafts, props and rudders. In contrast most trawlers seem to have a keel for directional stability and running gear protection.
This big boat business is all new to me, but I plan on getting one for serious cruising when i retire in a couple of years. I dont want to make a mistake.

Am I exaggerating the problem? Can you run a boat like that at 8 knots, or will it be unable to hold a heading?

Thanks for any comments.
__________________
Advertisement

Pluto is online now   Reply With Quote
Old 05-08-2013, 09:01 PM   #2
Master and Commander
 
markpierce's Avatar
 
City: Vallejo CA
Country: USA
Vessel Name: Carquinez Coot
Vessel Model: 2011 Seahorse Marine Coot hull #6
Join Date: Sep 2010
Posts: 10,265
Uh oh. Deadhead ahead, in the middle of the channel for the Antioch (CA) Bridge:



I place high priority on propeller/shaft/rudder protection (along with 360-degree decks/visibility and strong/high railings.)
__________________

__________________
Kar-KEEN-ez Koot
markpierce is offline   Reply With Quote
Old 05-08-2013, 09:11 PM   #3
Guru
 
motion30's Avatar
 
Join Date: Jan 2010
Posts: 740
I had a single engine Marine trader that I run aground multiple times ,never hurt a prop or running gear . I now have a twin engine boat ,I ran aground one time in the Bahamas and had to buy 2 new props I miss my little single engine boat . the ironic part is I spend most of my time in the new boat running the same speed I did in the.single engine boat
motion30 is offline   Reply With Quote
Old 05-08-2013, 10:41 PM   #4
TF Site Team
 
ksanders's Avatar
 
City: SEWARD ALASKA
Country: USA
Vessel Name: LISAS WAY
Vessel Model: BAYLINER 4788
Join Date: Feb 2011
Posts: 3,956
Pluto

A twin engine trawler style boat generally leaves the running gear exposed, except for the limited protection the keel provides.

A single engine boat, as you noted offers significant protection to the running gear.

This concept has been, and will continue to be, the root cause of many passionate discussions here on TF, on the docks, and amongst boating enthusiasts for as long as we have boats with props.
__________________
Kevin Sanders
Bayliner 4788
Seward, Alaska
www.mvlisasway.com
ksanders is offline   Reply With Quote
Old 05-08-2013, 11:00 PM   #5
Scraping Paint
 
City: -
Country: -
Join Date: Oct 2007
Posts: 13,748
The Grand Banks hull is nice in that in the twin engine models if the boat is grounded and the tide goes out, the running gear will not be damaged. This is because the shafts, struts, props, and rudders are located pretty close in to the fairly deep keel. (photo) So as the tide goes out and the boat goes over it will end up resting on the keel and the chine with the downside prop, rudder, and struts totally "protected" inside the resulting triangle of open space.

In the almost fifteen years that we've been doing this kind of boating we know or know of more owners of single engine boats (including sailboats) who have damaged their prop or rudder by hitting something or getting something wound up in the prop or shaft than we do twin engine owners who've had the same problems. I don't know if this is because twin drivers tend to be more vigilant about what's in the water ahead of them knowing their running gear is more exposed, where the single engine drivers blissfully cruise along assuming their prop, shaft, and rudder is suitably protected by the keel. In any event, twins or singles, it seems to make no real difference in the kinds of boats here that incur damage from debris, lines, nets, or a grounding.

We have a twin and so pay pretty close attention to what's in front of us. In situations where our course takes us close to or through fields of commercial crab pot floats both of us will be at the helm station looking ahead to pick a safe course through the obstacles. Same thing if the light is such that it makes stuff on the water hard to see. We'll both scan ahead of us to make sure we don't run over anything. If the water is calm most of the commercial crab pot floats show up quite well on radar, too, as they usually incorporate a large metal fender washer in their lashup.

Click image for larger version

Name:	image-3061743050.jpg
Views:	227
Size:	35.4 KB
ID:	19117
Marin is offline   Reply With Quote
Old 05-08-2013, 11:18 PM   #6
Guru
 
timjet's Avatar
 
Join Date: Apr 2009
Posts: 1,905
Quote:
Originally Posted by Pluto View Post
But when i look at their type of boat out of the water, I see v hulls with small rudders and extremly exposed drive shafts and props. ( I guess so they can go fast) My first thought when i see this is whats going to happen with a hard grounding or hitting a submerged object at speed? Seems to me you could take out the whole damn thing with bent shafts, props and rudders.

Thanks for any comments.
You pretty much nailed it though no hull design is going to survive hitting the submerged object in Marks post.

If you want to go fast you're going to have to give up the protection a large keel and hull design provides or be happy at sailboat speeds.

I am much more careful about watching the depth in my current boat than when I had a sailboat. But I also can make it across the Gulfstream to the Bahamas in 4 hours or across the FL straits to Key West in half a day, not possible at Trawler speeds.

In the many boat yards I've been around I haven't see a slew of Carvers, Sea Rays, or Bayliners with bent shafts and twisted rudders, but it does happen.
__________________
Tim
Tampa Bay
Carver 355 ACMY Twin Cummins Diesels Sold
timjet is offline   Reply With Quote
Old 05-08-2013, 11:22 PM   #7
Guru
 
Daddyo's Avatar


 
City: Cruising East Coast US
Country: USA
Vessel Name: Grace
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 2,441
The DeFever way! It certainly isn't as protected as the singles on my former boats, but that stuff is pretty damned robust
those are 24" wheels. The rudders are on the order of 30+" tall. The keel is 10" or so thick.
Attached Thumbnails
Click image for larger version

Name:	IMAG1503.jpg
Views:	181
Size:	130.4 KB
ID:	19119   Click image for larger version

Name:	IMAG2283.jpg
Views:	150
Size:	92.5 KB
ID:	19120  
__________________
Mark Bowerman
Brokerage owner and cruiser
Esse Quam Videri
http://graceyachting.com/
Daddyo is offline   Reply With Quote
Old 05-09-2013, 12:34 AM   #8
Senior Member
 
City: Pittsburg, CA
Country: USA
Vessel Name: NoMoBoat
Vessel Model: Trawlers
Join Date: Dec 2012
Posts: 278
Mark,

Being out of Antioch and often passing the 160 bridge, I do not ever recall having seen this particular landmark.
Any chance you might have the GPS coordinates for it?

Thanks.
__________________
JimS on the Delta
Delta_JimS is offline   Reply With Quote
Old 05-09-2013, 12:40 AM   #9
Master and Commander
 
markpierce's Avatar
 
City: Vallejo CA
Country: USA
Vessel Name: Carquinez Coot
Vessel Model: 2011 Seahorse Marine Coot hull #6
Join Date: Sep 2010
Posts: 10,265
Jim, it was immediately west of the Antioch Bridge, in the main channel on April 25. It wasn't there/visible when we returned several days later. Presumably, it's slowly working its way westward.
__________________
Kar-KEEN-ez Koot
markpierce is offline   Reply With Quote
Old 05-09-2013, 05:47 AM   #10
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,531
Not only is the running gear better protected but the singles prop can be far larger in diameter and spun slower.

This reduces noise aboard and makes better prop efficiency.

Go fast is one style of boating , but running the go fast at displacement speeds requires many compromises.

Poorer efficiency with perhaps iffy steering and a poorer ride .

But it can be done.
FF is offline   Reply With Quote
Old 05-09-2013, 09:06 AM   #11
Guru
 
Daddyo's Avatar


 
City: Cruising East Coast US
Country: USA
Vessel Name: Grace
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 2,441
Max prop size is not a function of single vs twin. It comes down to shaft angle ie. clearance from hull and/or skeg. We have the clearance for 36+" wheels yet twins.
__________________
Mark Bowerman
Brokerage owner and cruiser
Esse Quam Videri
http://graceyachting.com/
Daddyo is offline   Reply With Quote
Old 05-09-2013, 11:14 AM   #12
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,714
Daddyo, FF,
Unless you have a totally flat bottom (rare in a trawler) the twins will have significantly greater room for a larger dia prop w the same draft.

But re FFs comment some singles are built so deep that larger props can be used. But not on most all trawlers. Fishing boats yes.

On some deeper craft the optimum size prop is considerably smaller than the space available. If you have a large dia prop w lots of blade area and a very low pitch reducing the dia and increasing the pitch can increase efficiency. Over powered boats run out of prop space quickly though.
Attached Thumbnails
Click image for larger version

Name:	STH71262 copy 2.jpg
Views:	121
Size:	175.5 KB
ID:	19129  
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 05-09-2013, 12:52 PM   #13
Guru
 
Moonstruck's Avatar
 
City: Hailing Port: Charleston, SC
Country: USA
Vessel Name: Moonstruck
Vessel Model: Sabre 42 Hardtop Express
Join Date: Nov 2008
Posts: 7,851
Quote:
Originally Posted by motion30 View Post
I had a single engine Marine trader that I run aground multiple times ,never hurt a prop or running gear . I now have a twin engine boat ,I ran aground one time in the Bahamas and had to buy 2 new props I miss my little single engine boat . the ironic part is I spend most of my time in the new boat running the same speed I did in the.single engine boat
Usually when running aground in the Bahamas it is on a coral head. They can also cause hull damage. They will beat a prop until it's almost unrecognizable.
__________________
Don on Moonstruck
Sabre 42 Hardtop Express & Blackfin 25 CC
When cruising life is simpler, but on a grander scale (author unknown)
http://moonstruckblog.wordpress.com/
Moonstruck is online now   Reply With Quote
Old 05-09-2013, 01:12 PM   #14
Guru
 
Woodsong's Avatar
 
City: Atlanta
Country: USA
Vessel Model: Bayliner 4550 Pilothouse
Join Date: Oct 2007
Posts: 1,630
Some motor yachts have prop pockets and a smaller keel to at least get the keel a hair below the lowermost edge of the props to afford at least some protection to running gear.
Attached Thumbnails
Click image for larger version

Name:	photo-2.JPG
Views:	118
Size:	93.8 KB
ID:	19131  
Woodsong is offline   Reply With Quote
Old 05-09-2013, 01:15 PM   #15
Senior Member
 
rjtrane's Avatar
 
City: Palmetto Bay
Country: USA
Vessel Name: Sunshine
Vessel Model: Island Pilot DSe 12m Hybrid
Join Date: Apr 2013
Posts: 268
Pluto:


So far lots of discussion on singles vs. twins - protected props, etc.

Questions:

1. How do you intend to use the boat? Coastal? Ocean voyages? Weekends? Live aboard?

2. Size you're looking for and budget?

3. If you're NOT ocean voyaging , is speed when you want it important? There's no voyager I know of that has the option of planing-type speeds.

No sense in making any suggestions till one knows your answers.
__________________
Reuben Trane
"Sunshine" - Island Pilot DSe 12m
rjtrane is offline   Reply With Quote
Old 05-09-2013, 02:32 PM   #16
Guru
 
Brooksie's Avatar
 
City: Cape Cod, MA
Country: USA
Vessel Name: Island Seeker
Vessel Model: Willard 36 Sedan
Join Date: Oct 2007
Posts: 954
My father-in-law had a twin screw boat for years, said it gave him the protection against breakdown he needed. Bad load of fuel, I towed him in. One engine breakdown, he could only go in circles on the other engine, towed him in.

You know why they round over the aft top edge of rudders... So they won't pierce the hull when you bend over the shaft in a good hard grounding.
Brooksie is offline   Reply With Quote
Old 05-09-2013, 02:38 PM   #17
Guru
 
Moonstruck's Avatar
 
City: Hailing Port: Charleston, SC
Country: USA
Vessel Name: Moonstruck
Vessel Model: Sabre 42 Hardtop Express
Join Date: Nov 2008
Posts: 7,851
Quote:
Originally Posted by Brooksie View Post
. One engine breakdown, he could only go in circles on the other engine, towed him in.
Did the boat not have a wheel, or did he panic and forget to use it?
__________________
Don on Moonstruck
Sabre 42 Hardtop Express & Blackfin 25 CC
When cruising life is simpler, but on a grander scale (author unknown)
http://moonstruckblog.wordpress.com/
Moonstruck is online now   Reply With Quote
Old 05-09-2013, 02:43 PM   #18
Guru
 
Moonstruck's Avatar
 
City: Hailing Port: Charleston, SC
Country: USA
Vessel Name: Moonstruck
Vessel Model: Sabre 42 Hardtop Express
Join Date: Nov 2008
Posts: 7,851
Quote:
Originally Posted by Woodsong View Post
Some motor yachts have prop pockets and a smaller keel to at least get the keel a hair below the lowermost edge of the props to afford at least some protection to running gear.

__________________
Don on Moonstruck
Sabre 42 Hardtop Express & Blackfin 25 CC
When cruising life is simpler, but on a grander scale (author unknown)
http://moonstruckblog.wordpress.com/
Moonstruck is online now   Reply With Quote
Old 05-09-2013, 03:17 PM   #19
Guru
 
motion30's Avatar
 
Join Date: Jan 2010
Posts: 740
I know of a twin engine trojan that went hard a ground at.speed in the process driving the.struts up through the bottom of the boat sinking boat on the sandbar
motion30 is offline   Reply With Quote
Old 05-09-2013, 03:25 PM   #20
Guru
 
Brooksie's Avatar
 
City: Cape Cod, MA
Country: USA
Vessel Name: Island Seeker
Vessel Model: Willard 36 Sedan
Join Date: Oct 2007
Posts: 954
Quote:
Originally Posted by Moonstruck View Post
Did the boat not have a wheel, or did he panic and forget to use it?
No panic, it would only go in circles ChrisCraft 30something express.
__________________

Brooksie 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 08:15 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