Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 08-12-2009, 13:43   #1
Registered User
 
w32honu's Avatar

Join Date: Dec 2009
Location: New Hampshire
Boat: Custom Marples 40 FC
Posts: 432
Images: 2
Big Boats and Outboard Power...

Hello Everyone,

Just signed up and curious whether there are any of us out there using small outboard motors as auxilliary power. If so........how effective and what size outboards for what size boat?

I know it may seem a common question, but I am in the process of designing a modification (o/b well) to push a 12,000# boat. The result will be a dramatic simplification of my systems. A huge increase in storage capacity. And would lighten the load a bit...........and improve my sailing performance.............

The intended use would be just to manuever in and out of port and in close quaters. All of the study and theory regarding h.p. and prop pitch......etc is fine. But it is the real world application that I am curious about. And so I turn to you good people.

Thanks in advance,

s
__________________

__________________
w32honu is offline   Reply With Quote
Old 08-12-2009, 14:24   #2
Senior Cruiser

Cruisers Forum Supporter

Join Date: Oct 2005
Location: Cruising NC, FL, Bahamas, TCI & VIs
Boat: 1964 Pearson Ariel 'Faith' / Pearson 424, sv Emerald Tide
Posts: 1,531
Thumbs up Outboard in a well.

This idea has worked out well on many boats with suitable hull types.

Take a look at James Baldwin's site, specifically;

The Inside Outboard

I have an outboard in a well, and LOVE it for the same reasons you listed.
__________________

__________________
s/v 'Faith' is offline   Reply With Quote
Old 08-12-2009, 14:33   #3
Registered User
 
Pappy Chris's Avatar

Join Date: Dec 2009
Location: Aransas Pass TX
Boat: 1977 Marine Trader 40' Trawler
Posts: 61
Send a message via Yahoo to Pappy Chris
I have a Luger Voyager Ketch 30' and displaces 9800lbs. It has a 15HP Evinrude electric start and remote controls. It's been used primarily as you've outlined. I had occasion to use it in 40kt wind on my beam going back to the marina. I motor'd about 4 miles at 1/2 throttle and had no problem. I have motor'd 3 miles to weather with no problem at all with it. It's proven to have ample power to push the boat whenever I've called on it. All Kansas lake sailing -- Chris
__________________
Confidence is going fishing for Moby Dick in a row boat and taking the tarter sauce with you. (Zig Z).
Pappy Chris is offline   Reply With Quote
Old 08-12-2009, 15:46   #4
Registered User
 
beau's Avatar

Join Date: Dec 2006
Location: Brisbane Australia
Posts: 757
Images: 1
Make sure you get a "high thrust" outboard, which has a bigger prop and lower geared
__________________
beau is offline   Reply With Quote
Old 08-12-2009, 17:24   #5
Registered User
 
w32honu's Avatar

Join Date: Dec 2009
Location: New Hampshire
Boat: Custom Marples 40 FC
Posts: 432
Images: 2
Faith,

Thanks for the post guys. Curious what size o/b you are currently using in your well.

And thanks for the link. I have had the opportunity to talk with James Baldwin in the past. Definately some good ideas...........

Detracters would argue that there would be an exponential loss in ability to motor. This may be true. But I am most curious about the degree of loss and thus the trade off for increased sailing performance and all of the other benefits previously mentioned. I guess it is just a matter of priority.

My attempt here is to get an idea of the amount of displacement vs the amount of h.p.

Thanks again,

Cheers

S
__________________
w32honu is offline   Reply With Quote
Old 08-12-2009, 17:38   #6
Registered User
 
beau's Avatar

Join Date: Dec 2006
Location: Brisbane Australia
Posts: 757
Images: 1
the general rule is 5hp per ton for displacement speed.
__________________
beau is offline   Reply With Quote
Old 09-12-2009, 11:26   #7
Senior Cruiser
 
SkiprJohn's Avatar

Cruisers Forum Supporter

Join Date: May 2006
Location: Kea'au, Big Island, Hawaii
Boat: Cascade, Sloop, 42 - "Casual"
Posts: 14,192
Over the years I've used outboards and inboards in various conditions. For your stated purpose an outboard in a well would be a fine idea. For at sea in rough conditions I would prefer an inboard.
Here are some of the problems I've noted lately using an outboard on a Columbia 28, a Folkboat 26, a Wharram 23 cat and a WWP 19. Gas fumes below decks, raising and lowering the engine to keep the prop leg clear of the water while sailing and reaching the controls while steering the boat. If you can design your well with enough vertical space to raise and lower the outboard and close off the hole in the bottom of your boat as well as keep fumes from leaking into the cabin and have remote engine controls you will have a pretty great system. An electric start 10 hp 4 cycle would be all you'd need for the purpose you stated. Of course, you could get a larger engine if you want but remember the raising and lowering problem and weight of the engine.
regards
__________________
John
SkiprJohn is offline   Reply With Quote
Old 09-12-2009, 11:40   #8
Senior Cruiser

Cruisers Forum Supporter

Join Date: Apr 2008
Posts: 769
I've sometimes wondered why we don't store our dinghy outboards on brackets that would allow them to function as emergency backup to the inboard.
__________________
anotherT34C is offline   Reply With Quote
Old 09-12-2009, 12:43   #9
Registered User
 
Pappy Chris's Avatar

Join Date: Dec 2009
Location: Aransas Pass TX
Boat: 1977 Marine Trader 40' Trawler
Posts: 61
Send a message via Yahoo to Pappy Chris
The raising and lowering with 1 hand I agree can be a bear some times. Before I decided to sell my Luger I was in the process of engineering a way to use an salvaged tilt trim system from a Mercrusier I/O to raise and lower as necessary with a switch. Even had a design on spring loaded doors to close the bottom of the well when it was retracted. Now its winter in Kansas and I am selling it... no time now to complete it
I did use 2- 3" bilge blowers (1 push 1 pull) and hose to vent the well area out the stern but in Luger's the well is pretty well sealed and separated from the cabin interior anyhow. I have 2 louvered vents on the sides and 2 on the stern.
__________________
Confidence is going fishing for Moby Dick in a row boat and taking the tarter sauce with you. (Zig Z).
Pappy Chris is offline   Reply With Quote
Old 09-12-2009, 12:48   #10
Registered User
 
Pappy Chris's Avatar

Join Date: Dec 2009
Location: Aransas Pass TX
Boat: 1977 Marine Trader 40' Trawler
Posts: 61
Send a message via Yahoo to Pappy Chris
Correction

Quote:
Originally Posted by Pappy Chris View Post
I have a Luger Voyager Ketch 30' and displaces 9800lbs. It has a 15HP Evinrude electric start and remote controls. It's been used primarily as you've outlined. I had occasion to use it in 40kt wind on my beam going back to the marina. I motor'd about 4 miles at 1/2 throttle and had no problem. I have motor'd 3 miles to weather with no problem at all with it. It's proven to have ample power to push the boat whenever I've called on it. All Kansas lake sailing -- Chris
Correction. Luger Voyager 30's displace 8800 lbs.

OOOPs!
__________________
Confidence is going fishing for Moby Dick in a row boat and taking the tarter sauce with you. (Zig Z).
Pappy Chris is offline   Reply With Quote
Old 09-12-2009, 13:24   #11
Registered User

Join Date: Dec 2009
Location: Ontario
Boat: 5 m Bolger runabout, plus a Starwind 860 power tri under construction
Posts: 248
An outboard of 5 to 20 hp, on a retractable bracket, is quite a common choice for auxiliary power around here on sailboats of 18 to 26 feet or so.

It's a logical choice for a boat with few systems, low electrical demand and limited space, that will only be under power while in the marina. Some of the common problems- hard to lift up, etc.- can be avoided with balancing springs, clever linkages, etc. A well might be tricky to seal in such a way that the water flow under the hull isn't disrupted, though, and takes up space just like an inboard. I would be much more inclined to just add a bracket on the transom, unless the hull was originally designed with a motor well. Several o/b manufacturers have "big foot" or "high thrust" lines with larger diameter props, steeper gear reduction, and sometimes a better alternator, that are better suited to a sailboat then the standard versions.

The downsides, of course, are that powering in a rough seaway is problematic, and the electrical output of these small outboards can barely keep a battery charged well enough to run nav lights and a VHF. And converting an existing, inboard-engine boat to outboard-in-well or outboard-on-bracket is unlikely to do anything nice to its resale value.
__________________

__________________
Matt Marsh
marshmat is offline   Reply With Quote
Reply

Tags
outboard

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
Power Loss in Tohatsu 5HP Outboard ssullivan Engines and Propulsion Systems 64 30-11-2015 14:17
Big Little Boats Greenman Monohull Sailboats 13 11-01-2010 19:13
Why Big HP Difference in Sail/Power Cats? NorthPaul Multihull Sailboats 5 12-08-2009 16:17
Big Dog Boats OldSchool Families, Kids and Pets Afloat 11 25-03-2009 23:06
How big do they make fiberglass boats? brian and clare Construction, Maintenance & Refit 11 12-07-2007 08:22



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 09:31.


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.