Association Forum - Another OB question

Assn Members Area · Join

Home.

Association Forum

Ships Store

Cruising

Racing

Technical Tips

Photo Gallery - New

Boat Search - Updated

Manuals & Brochures

Swap Meet

Links

Officer Flag Line & Staff

Bylaws & Constitution

Members Area

Join the Association

Notice:
The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.

Association Forum

Username:	Password:
Save Password
Forgot your Password?

All Forums

Catalina/Capri 25/250 Sailor's Forums

General Sailing Forum

Another OB question

New Topic

Topic Locked

Printer Friendly

Author

Topic

Prospector
Master Marine Consultant

Member Avatar

Canada
3159 Posts

Initially Posted - 07/29/2008 : 10:38:41

I have read so much about how evil cavitation is, but what bout the opposite - When motoring with a following sea, what about waves swamping the engine? this past week we had the engine underwater more than twice. It never stopped running (miracle!) but if it had we'd have been in trouble.

Is there anything that can be done to prevent the problem, or is there somethign we should be doing differently?

"Iris"
1984 FK/SR #4040
http://frosthaus.blogspot.com/

Take a minute to register your boat with the association!!
http://www.catalina-capri-25s.org/owner_questionnaire.htm

Edited by - on

Stardog
Captain

Members Avatar

USA
319 Posts

Response Posted - 07/29/2008 : 10:54:25

It's certainly possible to swamp an engine. There are a couple of things to consider in mounting: When topping a wave the screw may come out of the water and this can cause damage to the engine, therefore the motor must be mounted so the screw is as deep in the water as possible; Also, the engine can be stalled if pooped by a following wave, so it must be mounted high enough to prevent this. The best that can be hoped for is a reasonable compromise between the lowest and highest mounting possitions. If your engine does not have a very long shaft, you might seriously consider getting one. Outboard engines are generally only used for manoeuvering in marinas, or when there is no wind and you have to get somewhere, or for emergencies. The last reason is the one you should be concerned with. If you have large waves, limited ability to manoeuver and lee shore, that is when you're going to wish you had that long-shaft.

Edited by - on

mhartong
Navigator

Members Avatar

USA
152 Posts

Response Posted - 07/29/2008 : 11:23:29

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Prospector</i>
[Is there anything that can be done to prevent the problem, or is there somethign we should be doing differently?
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

How bout replacing the outboard with an inboard ?

Edited by - on

Sloop Smitten
Master Marine Consultant

Members Avatar

USA
1181 Posts

Response Posted - 07/29/2008 : 12:21:26

I'm probably not telling you anything you did not already know but if you run at about 45 degrees to the swells you will limit their ability to swamp your engine. I have a long shaft motor (not an extra long shaft) and suffered through this quite a bit the first couple of years. It hasn't been as much a problem lately because I either motor so the waves aren't directly astern or cut the motor and sail. Last time it happened a powerboater caught me with a huge wake as I entered the harbor, spun me around like a top on my keel and doused the engine. If you have passengers with you make sure they are not all sitting in the cockpit. If you move some of that weight forward, sometimes it helps.

Edited by - on

Dave Bristle
Master Marine Consultant

Members Avatar

Djibouti
10005 Posts

Response Posted - 07/29/2008 : 14:18:56

Even if you don't have an XL shaft, the XL only gives you another 5", part of which you'd probably use to get the prop deeper... so your powerhead won't be a lot higher. Similarly, you could lift the bracket to the notch above the lowest (if that will still keep the prop wet), but I suspect that won't keep a wave from dunking the engine.

I'd say your best strategy is to avoid going dead-down-sea in big chop. Staying some 30 degrees off (zig-zagging if necessary) will help the waves to lift the stern rather than crashing in on it.

Edited by - on

Dave5041
Former Mainsheet Editor

Members Avatar

USA
3758 Posts

Response Posted - 07/29/2008 : 14:39:01

A brief dunking is usually not a problem, but if it is submerged long enough for water to flood under the cowling and down the intake, your engine stops and is probably going to be toast. Newer engines have rev limiters, so the issue becomes cooling water when the prop is out of the water. Again, a brief rise probably won't hurt. Older two strokes don't breath well at higher rpms, so they can tolerate some brief over-revving. It is best to keep a hand on the throttle to limit wear and tear and possible damage. My extra long shafts (old and new) have both been out of the water in 3-4 footers. Watch your throttle and speed - as you approach hull speed, the stern squats in the water as you increase throttle and puts your engine deeper. In really difficult conditions you should only go fast enough to maintain control.

Edited by - on

Topic

New Topic

Topic Locked

Printer Friendly

Jump To:

Association Forum

Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.