If the storm waves are large enough to severely damage the marina where your slip is located, all bets are off such as this map of storm wave heights, shown below:
"GRAND HAVEN, MI — An unseasonably strong storm system is poised to churn up the Great Lakes during the afternoon Wednesday.
National Weather Service forecasters expect Lake Michigan breakers to build to an impressive — yet dangerous — 10 feet or greater, especially out to mid lake. However, shoreline communities from about Saugatuck north to Holland and Grand Haven could see wave heights surge to at least 6 to 8 feet.
Considering Great Lakes water levels around long-term averages, the expected surf easily could inundate piers and other structures, meteorologist Bob Dukesherer said.
Winds are forecast to blow in excess of 20-30 mph from the south southwest.
"With 10-footers on top of water levels near normal, (that'll) swamp the piers more easily," he said. "
Sailing or motoring into the slip need not be an adventure in preventing a 5000 lb Nonsuch 22 from ploughing into the dock end of the slip. I have installed two 1.5" three strand dock lines, crossing the end of the slip, creating what I call a Cat Catcher, to take care of that situation.
Each end of the crossing dock lines are spliced onto galvanized thimbles, and fastened to eyebolts with galvanized shackles. The two crossing lines are pulled as tight as I could pull them by hand so the is very little sag in the two lines.
Docking is simply coasting into the center of the slip with enough speed to maintain steerage into the Cat Catcher. The bow slides along either of the fixed dock lines to the center of the crossing lines and the boat stops, with the bow in the center of the X, and the boat will then be gently sprung back a few inches from the X of the fixed lines.
One side of the stern will be closer to the edge of the slip than the other. Get off onto the dock on that side. Before you touch any other lines, walk forward along the dock and take care of the bow lines. This sequence, described below, is most important for ease of single handed docking.
The position of the bow lines on the dock, well forward of the bow when the Nonsuch has all 8 lines in place provides enough slack for the bow lines to be attached from the dock. To do so, position the bow cleat, or Sampson post, on the bow of the boat, straight out from the dock end of the first bow line to be attached. Pull the bow close enough to stand on the dock and drop that bow line over the post. Then walk around the dock end of the slip and drop the second dock line over the same cleat, or Sampson post, as well. This is easily done as long as none of the other six dock lines are yet attached to the boat. With both bow lines in place, walk along the windward side of the slip and attach the two spring lines over the midship cleat.
Continue along that windward side of the boat and drop the stern line over the stern cleat. The slip I am using is a few feet shorter than ideal so that the stern lines are not led quite as far behind the boat as would be ideal, but the 4 spring lines are more than heavy enough to keep the boat from surging forward and back in the slip without any further help from the stern lines.
Then walk around to the leeward side of the boat, and drop the two spring lines around the mid ship cleat, and then drop the stern line over the stern cleat.
How did this method of docking become important to me? When I first brought a much larger 36' cat rigged ketch to San Francisco Bay from the Great Lakes in April 1979, The only slip I could find in the Bay area was at the San Francisco Pier 39 marina. The floating strings of truck tires for the breakwater in use the first years after construction of that marina were useful for keeping wind wave chop out of the marina, but useless against the wake surge waves from passing naval ships, oil tankers, and container ships. When I came to the Pier 39 marina office, the damage to boats hurled onto one or the other of the pier fingers by wake surges, and winter storm swell surges, had reduced the number slip occupants from an estimated 10 year waiting list down to one slip available, so I took it.
Why were so many boats damaged? It seems that many of the boats had moved to Pier 39 from a well sheltered marina where there were modest sized wake surges. The owners were used to using only 4 dock lines, with almost no slack in those lines, and some fenders, to keep the boat off the sides of the slip. In my year there, before the newer Pier 39 breakwater walls were constructed, my light weight, high top sided 36 footer, never touched the sides of the slip fingers.
Since I was usually sailing single hand or double handed, into a marina with currents and surge waves, catching the bow in the X of dock lines and then, before the boat was pushed against the down wind or down current side of the slip, (which ever was dominant in slip) it was important to secure the bow lines first, followed quickly by the spring lines and the stern line on the windward side of the slip. The spring lines and stern line on the leeward side of the slip are connected last.