After picking up a rope with my prop a few years ago, I am still thinking to hang an outboard on the stern who can bring me home when something with the single Iveco or drive breaks down.the question is how much horsepower i need.An old calculation program on my pc gives 5 kn. with 20 hp and only 6 kn with 100 hp.The problem is a bit that going home to the marina i have to go via the Westerschelde sea arm (like your Thames) where the current reach easy 4 to sometimes 6 kn. So waiting for the tide to turn looks, beside placing another Iveco beside the existing one, the only option.
Question: What's the bowspeed of a Lochin 33 ? And how much power is needed to reach that speed ?
I have often thought of something similar on my single engined Lochin. I don't know what the calculations are to find the hull speed of a semi planing hull but I don't think you would need a huge amount to achieve a reasonable ''get home'' speed of 4 to 5 knots, we get that and more at about tickover in gear. A decent high thrust 4 stroke would be adequate. The main reason of not going down that road has been that I don't really want 25 litres of petrol hanging about on or under deck. If you know of a diesel engined outboard that was light enough and cheap enough then it would be an ideal solution. You would also need a decent drop/slide down bracket made, the off the shelf ones aren't really adequate for engines over 5hp even if they say they are good for 15hp
This is a concern I also have and there isn't an easy answer. We have to regularly drop divers under cliffs very close to rocks and when we go into dodgy areas we tow a 12' tender with a 10hp engine (which will tow the Lochin in calm conditions).
We also have an oversized spare anchor and very long rope. With the tender we can drop the anchor as far as the rope will reach and winch the boat to safety. If we then can't fix the problem we radio for help. I hope we never have to do it.
I believe Coventry Climax and Lombardini made diesel outboards but they wern't a success. They were very noisy and heavy compared to the equivelant petrols. For tax reasons there was never a market for their development.
I also tow a 13 ft tender with a 15hp outboard for the same reason and have the anchor/rope system as a back up. Two weeks ago I was backing off the pier and putting the helm over when the rudder folded back into the prop!!! Huge bang and stalled the engine, we had a full compliment of passengers aboard who didn't seem to realise we had a problem. We were just about to drop anchor when we got a short tow to a mooring where we could investigate what had happened (at that stage we didn't know for sure). End of trip and we had to ferry the passengers ashore in the dinghy. Sorted the rudder the next day and fitted my old spare prop, bent the new one but not too badly and were back in action the day after. It would have been much worse if it had happened at sea but we could probably have towed ourselves home with the dinghy but it does get you wondering. Sometimes we have to pass through some narrow reefs with big swells and I always give a silent prayer to the merciful gods of diesel propulsion to keep going for a short while more. We ended up welding some square bar to the skeg at the limit of the rudder travel so in theory it can never happen again. I am also going to change the helm pump and ram and install new hoses so I don't contaminate my new autohelm pump - the oil in the old system was black and gritty. So complete new steering system, not cheap but what price do you put on peace of mind especially when you try to make your living with your boat.
Getting back to the diesel outboards when I worked at the fish farm years ago they had a couple of Yanmar diesel outboards. They were very heavy and quite noisy but worst of all was the cost, they were into the teens of thousands of pounds each then, so I dread to think what they would cost now. Maybe some place like India makes diesel outbnoards, they make diesel motorbikes! If I find anything I'll let you know
thanks, never thought about petrol tank and fumes. About the peace of mind, I take (free of charge) 3 times a year 10 cildren out for fishing. Imagine..........................
My first idea was to place a Z drive on the stern, coupled to an oil motor a few hoses, oil cooler, 80 hp diesel (place enough under the deck and Tommie can use a little weight on the starboard stern anyway) connected to an oil pump, oiltank a few 24 v electric hyraulic valves and sailing, but for the calculated amount of money invalved, a tugboat companie will bring me home 3 times a year for the rest of my life.
maybe its possible to mount an oilmotor on an old outboard tail ??
