For more than a week I worked on the last things to be done until that day. OBM tackled during the weekend and the national holiday in her very special and focused way cleaning the interior. She did an excellent job. On the 20st at close to 0400 we both were exhausted, took a shower and went home. I tackled the rest on the 21th and MaRe was ready for splashing back into her world of the sea water.
On the 22nd, at 0930 the team from the Cotton Harbor Boat Yard came to moved MaRe into the water. The Volvo technicians were on board and we departed for the sea trial. They had checklist prepared. We increased in steps the RPM.
Then suddenly again white “smoke”, steam, came out of the PRT exhaust. Not enough cooling.
Another observation was that not enough seawater came out of the PRT muffler.
We went back to pier and they checked the impeller of the raw water pump which was not replaced during the maintenance. It turned out that there was a one blade had fissure which reduces the raw water (seawater) cooling water.
The steam disappeared but the amount of seawater coming out of the PRT exhaust was not enough. Especially at higher RPMs this was clearly to be seen.
As it was considered that the sea trial only takes an hour and we are back by lunch, an old friend from the days of the Kenwood Cup in Hawai came by. Nakanishi-san was at Kenwood in charge of organizing all and especially the media. That why Makiko worked for him in the press center during the biannual Kenwood Cup days. It was good seeing him again still being and good shape and working still a few month a year using his media connections. The boat yard people welcome him very friendly and offered him to place in meeting room where he could relax from the heat of the outside temperature being close to 40 degC. Unfortunately of the problems with the PRT engine I could not talk as long as wanted with Nakanishi-san. When Makiko arrived I needed to go back to the boat.
The technicians exchanged the raw water pumps between the two engines. On STB, the full amount of water came out of the muffler, but not in PRT. So the raw water pumps are not the cause.
A few other test were made and then it was decided to connect the PRT engine’s raw water intake to the genset’s raw water intake. Result, a full flow of water came out of the PRT muffler. A few other test were made and then it was decided to connect the PRT engine’s raw water intake to the genset’s raw water intake. Result, a full flow of water came out of the PRT muffler.
The Volvo technicians called their management and got approval to continue working. So they talked with the boat yard people. The full team got back to lift MaRe again out of the water.
MaRe, still hanging in the traveler lift belts it was found that a shell got loose from the inner side of the sail drive and was sucked up with increasing RPMs to the entrance of the raw water pipe inside the sail drive and reduced the water intake flow. With a screw driver the shell could be broken into pieces and the debris where flushed out first with pressed air and then with fresh water from a hose connected to the first raw water hose of the cooling system.
MaRe was launched again into the water. Starting the PRT engine, showed the full amount of sea water came out of the PRT muffler. Successful repair!!!
We moved MaRe to the pier where she could be docked until departure to Arari bay. There, the technician finished the PRT engine by removing all cooling short cuts for testing, replaced the fresh water of the inner cooling circuit with coolant and cleaned up all. We all were exhausted but happy the sea trial could be completed successfully.
This event showed me what I was years afraid of since years. The design of the raw water intake for the Volvos via the sail drive it not as good as it should be. Either the design of the inlet at the sail drive housing needs to be changed or a separate hull-through would be needed. Fortunately I have a deck wash pump, which – if needed – can be used to flush a sail drive in the opposite direction to get debris of shells out while MaRe is in the water and cannot be lifted out.
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