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maxingout · 10-07-2010, 12:08

Quote:

Originally Posted by mikefp60

Check out this blob of fun. 400 miles north of Virgin Islands, middle of nowhere. Right into the prop.

That must have been fun to dive down and cut from your props. I was lucky because I had my son, David, to dive down for such challenges.

**David M** · 10-07-2010, 12:14

Quote:

Originally Posted by Astrid

I don't see why it wouldn't work, but what would be the drag figure for such a guard?

Increased is the only firm figure.

It depends on the design and the boat I would imagine.

btrayfors · 10-07-2010, 12:42

Funny, only one post came close to answering the OP's reasonable question with a workable response.

Hitting things in the water is de rigour on the Potomac, especially after heavy rains. We have tons of "Potomac alligators"....everything from tree branches to telephone poles, picnic tables, tires with rims (floating vertically or horizontally), and all manner of jetsom....simply not avoidable if you travel at night which I often do.

One technique which works very well if you're traveling at a reasonable speed, say under 10 knots or so: The instant you hear a bump on the bow or hull, simultaneously pull the throttle all the way back and a split second later pull the gear into neutral. Not reverse. Your boat speed will carry you past the point of impact and the object...whatever it might be...will bounce along the bottom of your hull and will pass harmlessly behind you. Don't put the engine back into gear until you see the culprit floating in your wake.

Bill

SaucySailoress · 10-07-2010, 13:34

Yep, it's a problem. When on paasge from Bahrain to Kuwait we ALWAYS seem to hit the Saudi oilfields at night - no matter how well we try to time our departure...

This is a problem because it is dark, and when the flares are in front of you, you can barely see the surface. Plus there are unlit mooring barrels (they literally are just big barrels) for tankers. SO, once when it was flat calm, no moon, flares in front and three on the boat... we did two up, one down at night. I was on watch, sitting on the bow, watching the water. Even so, I didn't see the barrel that we ran over. No damage thankfully. But it doesn't matter how much care you take in some conditions....

sonnysoh · 11-07-2010, 19:34

Hello Fellow sailors, appreciate for all your thoughts on the above said subject. Will be very focus and attentive when sailing in the night. Thanks again for all the advise. Happy sailing.

bewitched · 11-07-2010, 19:37

Quote:

Originally Posted by btrayfors

The instant you hear a bump on the bow or hull, simultaneously pull the throttle all the way back and a split second later pull the gear into neutral. Not reverse.

I'd be interested to know why you say not reverse. I always try to get it into reverse. My thinking is (I have a maxiprop):

1: getting into reverse stops the prop from spinning and so is less likely to pick up anything.

2. selecting reverse gets the prop feathered. A feathered prop presents less surface area to be hit

3: A feathered prop also presents the edge of the blade to the object going under the boat - which is a stronger section than presenting the flat of the blade

SariTimur · 11-07-2010, 19:59

Actually putting the maxprop in reverse locks the prop open not feathered. Thus it would just start spinning backwards. According to max prop putting the prop into reverse before shutting down the engine is the way to keep the prop from feathering and allow you to run a shaft alternator.

captain58sailin · 11-07-2010, 20:02

When ever you have an impact on the hull, from floating object, it tends to drive the object down, and the forward motion of the vessel brings the object closer to your running gear. If you pull the engine out of gear the prop stops and there is no energy going to the prop from the engine, so it is free spinning, where if you put the vessel in reverse, there is still energy coming from the engine, and could possibly increase the damage. Due to the forward inertia you are unlikely to stop the vessel before the object reaches the prop, if she is out of gear it reduces the amount of energy on the prop and hopefully reducing the damage of the impact. Once you drift free of the object then you can continue on your merry way and hopefully the object did not strike your running gear. If you can tell on which side the object hit, it doesn't hurt to turn towards that side, either. This all has to be done immediately, if you have to stop and think about it, it is already too late.

bewitched · 11-07-2010, 20:21

Quote:

Originally Posted by SariTimur

Actually putting the maxprop in reverse locks the prop open not feathered. Thus it would just start spinning backwards. According to max prop putting the prop into reverse before shutting down the engine is the way to keep the prop from feathering and allow you to run a shaft alternator.

Putting the engine into reverse after it has been shut down will feather a maxprop.

so - hit an object, turn off the engine, select reverse - prop will feather.

Leaving it in neutral, the blades will be extended and it will spin.

EDIT - just realised there may be a misunderstanding - I turn the engine off first

SariTimur · 11-07-2010, 21:24

I have a hydraulic gear box so putting in reverse after the engine is off will not do any good. "The MaxProp is only designed to feather from forward gear" Their words. So going to neutral from forward it is most likely to feather. Going to reverse first will do the opposite. MaxProp also recommend for hydraulic gear boxs to shut the engine down while still in forward gear then going to neutral so as not in gear when you restart the engine.

bewitched · 11-07-2010, 22:09

The maxprop doesn't feather in neutral - or at least mine doesn't - you can hear it turning the shaft.

It only feathers when in gear - I'm not sure why I use reverse - probably because that's what I've seen other people doing.

When maxprop say that it only feathers from forward gear, what I think they mean is that it doesn't feather after you have using reverse gear to go backwards.

**Ex-Calif** · 11-07-2010, 22:26

Quote:

Originally Posted by bewitched

I'd be interested to know why you say not reverse. I always try to get it into reverse. My thinking is (I have a maxiprop):

1: getting into reverse stops the prop from spinning and so is less likely to pick up anything.

2. selecting reverse gets the prop feathered. A feathered prop presents less surface area to be hit

3: A feathered prop also presents the edge of the blade to the object going under the boat - which is a stronger section than presenting the flat of the blade

Quote:

Originally Posted by SariTimur

Actually putting the maxprop in reverse locks the prop open not feathered. Thus it would just start spinning backwards. According to max prop putting the prop into reverse before shutting down the engine is the way to keep the prop from feathering and allow you to run a shaft alternator.

Putting the engine in neutral regardless of the prop type is correct. A non-spinning prop or one that is only spinning with water current will have less chance of a wrap if the object is a rope and if it does wrap it will be a looser wrap.

In regards to a hard object hitting the prop I doubt you reduce your chances much with a feathered prop. This is one case where the folding prop probably wins over other types.

For a feathering prop getting the engine shut down and the prop feathered in a boat length is pretty heads up sailing and makes me wonder how someone so heads up could hit an object in the forst place -

In regards to getting the max prop feathered I always shut down in forward or neutral and then select reverse after the engine is stopped. I often hear the prop turning after shut down but it always stops when I select reverse. This is with a standard mechanical geared saildrive.

SariTimur · 11-07-2010, 22:27

I think we are starting to hijack this thread. But I think you are right you are shutting down your engine in forward as well then locking the shaft by putting it in gear. Probably would work in forward as well but those people with fixed props always locked them in reverse to stop prop spin. When we first started with the MaxProp we had some issues with it not feathering from neutral especially in heavy following seas or whent the boat was sailing too fast. I contacted MaxProp about this and they said to shut down the engine while still in forward gear. Worked great since then. Except to get this back on thread once when we picked up a piece of rope from Sebana without knowing it until we got to Pulau Aur. The rope had tangled up the prop enough to hold it open. I do love my MaxProp though so much better than the big fix laded prop that used to cook my gear box when it spun freely. So much so that I am carry a spare on this trip incase we pick up a log which they are all over the Rajang river (again to get back on to thread). And Sonny on the way from the Rajang to Miri we had some great sailing. But we hit several patches with lots of logs and branches. While sailing we seemed to have no worries but then we are full keel as well. But when motoring try to avoid items if you can't try hitting them at a slight angle and hope the prop wash and keel shape kick them out to the side. Seems to work with us more than 50% of the time direct head on hits seem to force the stuf under where it might pop up next to your prop and do the damage like you experienced.

Cheers