A dinghy foot pump comes to the rescue to clear a clogged saildrive water intake.
Issue 144: May/June 2022
It was another spectacular summer day, and once again my wife, Carey, and I escaped life ashore aboard Natasha, our Islander Bahama 30, the trusty diesel humming beneath our feet as we eased out of the marina. The forecast promised sunshine and moderate winds. Friends were already in a beautiful anchorage 10 miles away, awaiting our arrival.
Light wind rippled the clear blue water as we passed the breakwater, boats skittering about like water bugs on a lake. Suddenly, an alarm that I’d not heard before shattered the idyllic scene. A quick scan of the engine panel showed a bright red warning light for engine temperature, the accompanying gauge reading well above normal and rising rapidly. Not good!
Bert’s dinghy foot pump and hose,
attached with a nylon adapter and
proper-sized hose clamp to the
raw-water intake hose, can quickly clear the saildrive’s inaccessible intakes.
I quicky shut down the diesel and scrambled to roll out the genoa to maintain steerage in the crowded channel. Fortunately, the breeze was just forward of the beam, and Natasha held a steady course on a tight reach.
Carey took the helm as I dove below to open the engine compartment. When I removed the companionway steps, a wave of heat billowed into my face. The heat exchanger was too hot to touch; I wasn’t going to open the coolant cap to check fluid levels. The raw-water strainer’s clear plastic top showed no debris—and no water, either.
I’m somewhat fanatical about engine maintenance, and I knew that the raw-water pump was almost new and probably not the cause. I called to Carey to momentarily start the engine; still, no water flooded into the strainer.
The strainer was mounted so that the top lip of the bowl was at seawater level. I knew that if I took the screw top off the strainer, water should quickly flood to the top of the plastic bowl. I did, and it didn’t. The hose between the raw-water intake and strainer showed no points of collapse. Something was plugging the intake.
I climbed back into the cockpit to assess our situation. We were about a mile from our berth at the marina, it was mid-afternoon on the first day of a four-day jaunt into the Canadian Gulf Islands, and our friends were waiting. The breeze was steady and from the right direction.
Our discussion was short: We’re on a sailboat, let’s go sailing! We hoisted the main to join the genoa, and the afternoon quickly vanished in a glorious three-hour reach to the anchorage. Diagnosis and repair could wait; cocktails, dinner, and good company under a setting sun took precedence.
The next morning, I reassessed the problem. Natasha was powered with a Beta 20 diesel mounted on a saildrive, a system I had installed nine years earlier and was very familiar with. The raw-water intake was through the saildrive leg protruding under the hull, much like the water intake of an outboard motor. What could have plugged the intakes on both sides of the leg?
The raw-water intakes on the saildrive are visible near its leading edge.
I had no intention of going for a swim in the 40°F water if I could help it. I started the Beta momentarily and put the prop in reverse, hoping the wash would force the obstruction away from the inlet ports. No luck.
I thought back to our old system, a Volvo MD7A diesel with a shaft and fixed prop. When we faced a water flow blockage, I would close the through-hull seacock and remove the intake hose. With a metal probe (usually a long ice pick), I would carefully open the seacock and start poking at the obstruction, usually kelp, as water started to geyser in—always an exciting and wet experience.
But I couldn’t do that with the saildrive leg. The water intake openings were just too far down the leg from the seacock mounted on the upper part of the leg inside the boat. There was no way to push the obstruction out.
It was time to improvise. I thought about Natasha’s dinghy, or, more specifically, the foot pump and hose that we used to inflate it. Although not identical in diameter, the pump’s hose lined up reasonably well with the raw-water hose I had removed from the intake port of the raw-water strainer. I taped the two hoses together using plenty of Rescue Tape (something every sailor should carry).
Natasha under sail. When the engine overheated, Bert and Carey opted to sail to their rendezvous, enjoy their evening, and work on the problem while at anchor the next day.
Carefully, I pressurized the raw-water intake hose leading into the leg. Nothing happened other than to pressurize the hoses, no sound of bubbles under the hull. Careful pressure eventually progressed to stomping on the pump. Suddenly, the pump went slack, and I could hear air bubbles escaping under the hull. Success!
I quickly shut the seacock at the leg before seawater flooded up into the foot pump. I separated the two hoses and reconnected the raw-water hose to the raw-water strainer. When I opened the seacock, the bowl quickly filled with water, and a start of the engine revealed excellent water flow. I never did see what had plugged the intakes, but we were back in business.
These sorts of problems always seem to happen at inopportune times, but next time, I’ll be ready. I now carry a nylon adaptor to connect the raw-water intake hose to the dinghy air pump hose, as well as two properly sized hose clamps (no more reaching for the Rescue Tape). This setup should also work well for a standard engine through-hull intake hose—no need to get wet as water pours into the boat.
Also, at next haulout, I’m going to install a second raw-water through-hull near the engine with a proper seacock, then T the new hose into the strainer hose. Should this problem crop up again, particularly around marinas and other tight places, I can simply open the seacock on the backup intake to keep the engine happy until I can sort out the blockage.
I have also installed an Aqualarm Cooling Water Flow Detector with alarm indicator on the engine control panel. This alarm will sound long before a blocked water intake becomes an issue at the engine, giving me ample opportunity to shut down before overheating. The diesel is too valuable—both as a reliable friend as well as a financial expense—to not catch such a failure in time.
Bert Vermeer and his wife, Carey, have been sailing the coast of British Columbia for more than 30 years. Natasha is their fourth boat (following a Balboa 20, an O’Day 25, and another Islander Bahama 30). Bert tends to rebuild his boats from the keel up. A retired police officer, he also maintains and repairs boats for several non-resident owners.
Thank you to Sailrite Enterprises, Inc., for providing free access to back issues of Good Old Boat through intellectual property rights. Sailrite.com
