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allstar1976 · 15-07-2014, 17:24

I'm new to sailing and made a bad decision to take friends out, just for a motor around the harbour. My slip is at the end of the dock at the furthes point out, i just had to push off the bow and go forward.. Well it didnt' work I have a Tanzer 22 with a 7.5hp motor... as soon as we untied the motor had no power and wouldn't move us we just drifted backwards... I thought at the time their must be something wrong with the motor.We got towed back to the slip and I tested the motor and the propeller seemed to work fine.. I know it's a small motor but shouldn't it have gotten me out of their? i should mention there was a 20 knot wind that day..

wingless · 15-07-2014, 17:32

Welcome to the forum and to boating.

If the motor was running, in gear and has a propeller w/o a spun hub, then it will develop thrust.

One novice error is insufficient engine RPM. Sometimes LOTS more throttle is required. Many get used to putting at idle, then forget more is required when wind and current push the boat.

Get and study Chapman's Piloting and Seamanship. It is the best single resource to learn about boating.

One method to get off the dock is to use a line to hold an end of the boat while the engine thrust causes the boat to pivot, then release the line.

allstar1976 · 15-07-2014, 17:52

Hmm i must have a motor problem than... i had it wide open and wouldn't move or turn

wingless · 15-07-2014, 18:02

Try securing the boat to the dock and see if the engine will push the boat within the confines of the line slack.

One "common" problem for small outboards is a sun propeller hub. This is the rubber bushing between the center hub and the blades. It is intended to fail / disengage if the blades hit something to reduce other damage to the motor.

Adventurebound · 15-07-2014, 18:04

I have your size boat and 5.8 hp. Having your sails bunched on the boom and around the forestay produces lots of drag. 20 kt winds can produce 30 kt gusts. If launching into the wind have some power on while releasing the rope. You probably were already drifting back before you applied power. Takes a while to overcome that momentum to start moving forward.

**Ex-Calif** · 15-07-2014, 18:09

In the initial launch was there water "churning" behind the prop?

I've been using a 5hp motor on my 2500kg boat as the diesel is out of commission. It is marginal and wont successfully push the boat against all winds and seas.

But 7.5 on your boat should be able to push against a 20kt wind - albeit probably slowly.

20kts is probably at the upper limit for your set up and experience level. You should think about your launching technique. I usually have a dock "walker' who stays on the dock as I am backing out. That person steps up to the bow when the bow clears the dock and sometimes (usually if I can manage it) after the boat is shifted in to forward.

I have had engine flame outs (hence the dead diesel) after back out. And then the drama starts as we fend off other boats and try to get back to the dock.

Then I started berthing stern-to and the dock walker walks the stern to the end of the finger before stepping on board. Solo I have used a loop on the end finger cleat that I "flip" off as the stern passes the end of the finger.

Bottom line is to try not to "cast off" until you know the boat is under its own motive power.

**Ex-Calif** · 15-07-2014, 18:11

Quote:

Originally Posted by wingless

Try securing the boat to the dock and see if the engine will push the boat within the confines of the line slack.

One "common" problem for small outboards is a sun propeller hub. This is the rubber bushing between the center hub and the blades. It is intended to fail / disengage if the blades hit something to reduce other damage to the motor.

Excellent point - a lot of small outboards have a shear pin device. It can look normally turning at low "in gear" speeds but slip like crazy under power.

Others simply use a friction device that can also slip.

rgscpat · 15-07-2014, 18:35

When did Mercury and Nissan and other makes go to the rubber hub instead of a shear pin and what is involved in "rehubbing"? I guess the bigger engines changed over earlier, and are some pressed hubs harder than those that are more designed for user replacement?

lockie · 15-07-2014, 18:54

Maybe I missed it, but I didn't see "outboard" in your OP. If it is an inboard, you might want to check for growth on the propeller: a heap of barnacles etc can reduce the prop thrust to bugger-all despite it rotating. If it is an outboard, just ignore me.

Cheers, Graeme

wingless · 15-07-2014, 20:30

Quote:

Originally Posted by lockie

Maybe I missed it, but I didn't see "outboard" in your OP. If it is an inboard, you might want to check for growth on the propeller: a heap of barnacles etc can reduce the prop thrust to bugger-all despite it rotating. If it is an outboard, just ignore me.

This reply to the OP's other topic has information on the OP's boat type, a Tanzer 22, showing that the engine is a small outboard.

S/V Alchemy · 16-07-2014, 10:23

Learn the term "warp off a dock" or "warping out of a slip". Basically, you run a loop of line to the aft bollard on the dock and motor against that. You pivot in reverse while still attached. Only when pointing in the right direction do you release the tail and haul in the line, carefully so as not to foul the prop.

Google is your friend as are Dutton, Chapman and RYA manuals.