MainlySteam
New member
While this boat is a bit longer than most forumite's ones (TCM and a few others excluded) some might be interested in a quick run down on what happens in sea trials on a boat going into commercial service with professional owners. May help with thinking towards testing ones own new boat. If not interested, stop reading here.
Last week attended the sea trials in Australia of a new build I have been managing since concept development - going to a client around your side of the world for passenger service for high quality commuting (one of the highest per capita GDP's in the world - aircraft type interior, music, TV, movies, small galley, etc) and tourists off cruise ships. Is 76 foot long, foil assisted catamaran (foil between hulls to provide lift and stability in turns) with around 3,000 hp to 4 water jet drives.
People present were the shipyard's representatives, the shipyard's skipper, the designer, the owner's mechanical and electrical chief engineers plus their chief skipper, the engine supplier's representative, the water jet manufacturer's representative, classification society surveyor and myself (representing the owner).
All days were around 12C and showery rain.
Day 1 Harbour Trial
Machinery had been run up beside dock previously. At dawn the yard and the designer's naval architects, and myself did the lightship measurements which entails measuring the vessels drafts and freeboards. I got to skipper the dinghy /forums/images/icons/smile.gif. The figures were stuck into the hydrostatics program and weights on and off allowed for (things on the boat not to stay on for service and things not yet installed) and the vessel's displacement and deadweight confirmed (had also been on load cells before launching).
Safety briefing by the yard's skipper - lifejackets, 25 man liferaft deployment, designated "crew" for managing any flooding accident and mustering, etc.
Started everything up and checked, lines let go and whoops first little ding /forums/images/icons/blush.gif. Those familiar with multi jetted boats will know that they can be driven sideways off docks (nozzles pushing sideways to push off, buckets up one side, buckets down the other to counter yaw) but something was wrong and not enough push from nozzles in desired direction and stern swung into the dock. Got away and the boat wanted to go round in circles (but could be held straight) - did a pile of runs and zig zags at various speeds to try and identify the problem. Got back onto dock after an hour or so of that.
Day 2 First Sea Trial
Yesterdays problem fixed by shipyard overnight and boat loaded up with full fuel and flooded forepeak and large containers of water on deck to replicate full load (180 pob). Did the draught/freeboard measurements again at dawn (yawn), fired everything up and off we went.
Went through all drive control systems (which included the steering, of course) with all tests recorded and witnessed. Checked all emergency shutdowns and restarted ship from black ship. Speed runs in two directions for small increments of engine revs from low to 100% power. Zig zags, turning and stopping (including crash stops) tests.
Was a bit bumpy at times with a ground swell and we had about 12 of the yard's fitout trades still on board working - several decorated the transom with technicolor offerings to the fishes and others were carrying buckets with them.
Evening I conducted a debrief in the hotel bar over appropriate refreshments.
Day 3 Second Sea Trial
Back at dawn (yawn, yawn) reballasted the boat for half deadweight - I had the cold task of part draining the forepeaks into the next compartments and pumping that out to reduce weight. Speed trials repeated as were turning and stopping. This day was the replication of 8 hours non stop service including duplicating service manoeuvres and 2 hours to run at full power with unattended engineroom (ie nothing allowed to need attention). Client's chief skipper got to drive much of this plus practice docking against a buoy (much to the disgust of a seal that had made it his home).
Debrief again in the evening.
Day 4 What'll She do Trial
Allowed to sleep in to start at 7am this day. Ship with no ballast, black water pumped out, half water and fuel and about 20 pob. Client's skipper is the driver off the dock and during day and back onto dock - does a good job. Various speed runs at various powers until the one all waiting for - got a smiggen over 40 knots with a wake to dream about - the boat was designed to hydrodynamically "fail" ie foil lift reduces, outer jet intakes start losing water at around 39.5 - 40 knots so was just as expected.
Did anchor trial also, pretty melodramatic. Evening debrief again.
All tests recorded - printed report of results is 22 pages and also includes all wind, sea, swell, and compass course for each so the above abridges the events somewhat.
May be of interest:
Highest speed observed - 40.2 knots (GPS)
Distance to stop from full speed - 5 boat lengths - throttles on full power, buckets straight from fully up to fully down - big warning to all on board to hold on. Crash stops were measured by radar.
360 turn diameter at full speed - less than 5 boat lengths. Again measured by radar.
360 turn at manoeuvring speed - within own length.
Heel in full lock turn at full speed - slight inwards heel (as some will know power cats normally tend to heel disconcertingly outwards in fast turns).
Most fuel/nm economical speed at half load - a couple of knots under full speed.
Exprapolating from the results it is expected that the 76 foot boat will get over the hump with 200 pob (ie say around mid 20's knots) and full tanks.
Thing I personally liked most - as a raggie in my private life I have to concede the nice cosy heated wheelhouse was very, very nice.
Thing I liked least - Out of bed at 5:30am after working to midnight evenings before, but after all they do call this stuff work /forums/images/icons/smile.gif.
John
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Last week attended the sea trials in Australia of a new build I have been managing since concept development - going to a client around your side of the world for passenger service for high quality commuting (one of the highest per capita GDP's in the world - aircraft type interior, music, TV, movies, small galley, etc) and tourists off cruise ships. Is 76 foot long, foil assisted catamaran (foil between hulls to provide lift and stability in turns) with around 3,000 hp to 4 water jet drives.
People present were the shipyard's representatives, the shipyard's skipper, the designer, the owner's mechanical and electrical chief engineers plus their chief skipper, the engine supplier's representative, the water jet manufacturer's representative, classification society surveyor and myself (representing the owner).
All days were around 12C and showery rain.
Day 1 Harbour Trial
Machinery had been run up beside dock previously. At dawn the yard and the designer's naval architects, and myself did the lightship measurements which entails measuring the vessels drafts and freeboards. I got to skipper the dinghy /forums/images/icons/smile.gif. The figures were stuck into the hydrostatics program and weights on and off allowed for (things on the boat not to stay on for service and things not yet installed) and the vessel's displacement and deadweight confirmed (had also been on load cells before launching).
Safety briefing by the yard's skipper - lifejackets, 25 man liferaft deployment, designated "crew" for managing any flooding accident and mustering, etc.
Started everything up and checked, lines let go and whoops first little ding /forums/images/icons/blush.gif. Those familiar with multi jetted boats will know that they can be driven sideways off docks (nozzles pushing sideways to push off, buckets up one side, buckets down the other to counter yaw) but something was wrong and not enough push from nozzles in desired direction and stern swung into the dock. Got away and the boat wanted to go round in circles (but could be held straight) - did a pile of runs and zig zags at various speeds to try and identify the problem. Got back onto dock after an hour or so of that.
Day 2 First Sea Trial
Yesterdays problem fixed by shipyard overnight and boat loaded up with full fuel and flooded forepeak and large containers of water on deck to replicate full load (180 pob). Did the draught/freeboard measurements again at dawn (yawn), fired everything up and off we went.
Went through all drive control systems (which included the steering, of course) with all tests recorded and witnessed. Checked all emergency shutdowns and restarted ship from black ship. Speed runs in two directions for small increments of engine revs from low to 100% power. Zig zags, turning and stopping (including crash stops) tests.
Was a bit bumpy at times with a ground swell and we had about 12 of the yard's fitout trades still on board working - several decorated the transom with technicolor offerings to the fishes and others were carrying buckets with them.
Evening I conducted a debrief in the hotel bar over appropriate refreshments.
Day 3 Second Sea Trial
Back at dawn (yawn, yawn) reballasted the boat for half deadweight - I had the cold task of part draining the forepeaks into the next compartments and pumping that out to reduce weight. Speed trials repeated as were turning and stopping. This day was the replication of 8 hours non stop service including duplicating service manoeuvres and 2 hours to run at full power with unattended engineroom (ie nothing allowed to need attention). Client's chief skipper got to drive much of this plus practice docking against a buoy (much to the disgust of a seal that had made it his home).
Debrief again in the evening.
Day 4 What'll She do Trial
Allowed to sleep in to start at 7am this day. Ship with no ballast, black water pumped out, half water and fuel and about 20 pob. Client's skipper is the driver off the dock and during day and back onto dock - does a good job. Various speed runs at various powers until the one all waiting for - got a smiggen over 40 knots with a wake to dream about - the boat was designed to hydrodynamically "fail" ie foil lift reduces, outer jet intakes start losing water at around 39.5 - 40 knots so was just as expected.
Did anchor trial also, pretty melodramatic. Evening debrief again.
All tests recorded - printed report of results is 22 pages and also includes all wind, sea, swell, and compass course for each so the above abridges the events somewhat.
May be of interest:
Highest speed observed - 40.2 knots (GPS)
Distance to stop from full speed - 5 boat lengths - throttles on full power, buckets straight from fully up to fully down - big warning to all on board to hold on. Crash stops were measured by radar.
360 turn diameter at full speed - less than 5 boat lengths. Again measured by radar.
360 turn at manoeuvring speed - within own length.
Heel in full lock turn at full speed - slight inwards heel (as some will know power cats normally tend to heel disconcertingly outwards in fast turns).
Most fuel/nm economical speed at half load - a couple of knots under full speed.
Exprapolating from the results it is expected that the 76 foot boat will get over the hump with 200 pob (ie say around mid 20's knots) and full tanks.
Thing I personally liked most - as a raggie in my private life I have to concede the nice cosy heated wheelhouse was very, very nice.
Thing I liked least - Out of bed at 5:30am after working to midnight evenings before, but after all they do call this stuff work /forums/images/icons/smile.gif.
John
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