RPM in reverse - how much is enough?

[Bratina]

Like many posters here, I've been at a point where reverse in my A4-powered Grampian 30 is low to non-existent.

I adjusted the reversing gear (one flat of the nut) towards the end of the season last year and it helped a little, although thrust in reverse remains extremely weak. I'm going to install an Indigo 3-blade prop over the winter, which many forum members have noted is more effective than a 2-blade. It's worth a shot, my boat is on the hard, and the cost is relatively low.

For no rational reason I baby my engine - I cringe when my RPMs climb over 2K, and cruise at between 1600 - 1800 (which nets me around 5kt - plenty for my short stint to get off the dock and out to Lake Ontario). I've read at length people noting that you have to 'really gun it' to get decent thrust backwards, but it's never quantified in terms of actual RPM.

So my question is twofold: what is 'gunning it' in reverse? I usually get to 2-2.2K RPM in reverse and, again irrationally, get scared. Likely part of my problem with the 'brakes'.

Second: a lot of forum members note that it's better for the engine to run at a higher RPM. Should I be scared cruising at 2,000 - 2,200 rpm or higher? Is it true that it's easier on the engine? If temperature and oil pressures are nominal, is it any more risky to run at 2,200 rpm vs. 1,800 rpm? It seems counterintuitive (and I should get a vacuum gauge...).

[sailhog]

Ahoy, Bratina! Others will chime in here, but here's an introductory two cents... The reverse gear on the A-4, I believe, is geared down a third to the forward gear.

Standby for more commentary...

[Sam]

I'll chime in a bit. Having an older heavy displacement boat, 1966 Morgan 34, with a 3/4 keel somewhat similar to the Grampian you just can not expect make much headway in reverse. The reverse "prop thrust " is hitting the very nearby keel. Reverse "gunning" the throttle stops the boat nicely and the prop walk gets me next to the dock but getting out, especially against the wind is difficult.

[ndutton]

A technique I learned with my previous full keel boat was to give her a burst of power in reverse to get her moving, then take her out of gear and let her coast. Steering is much more responsive without the prop turning.

[GregH]

Originally Posted by ndutton

A technique I learned with my previous full keel boat was to give her a burst of power in reverse to get her moving, then take her out of gear and let her coast. Steering is much more responsive without the prop turning.

Exactly what I have to do, and turn to starboard to get facing the right way in the marina channel. brief bursts with the tiller hard to port. The key for my situation is brief busts - say 3-5 sec.... coast... burst....coast...

now, add some wind coming from starboard...

[sastanley]

The reversing gear really screams when you rev it up to 2,000+ RPM, and I think until you are used to the noise, it scares people.

Also, newer users to the A4 may not realize they need to lean on the gear lever to hold pressure on the reversing band to keep the prop shaft fully engaged.