Member Removed Posted August 16, 2006 Report Share Posted August 16, 2006 anyone know what size auxilary engine would push a 21 foot boat along. not expecting anysort of speed just for safety, .. dave Quote Link to comment Share on other sites More sharing options...
britboard Posted August 16, 2006 Report Share Posted August 16, 2006 I would say you would want a minimum of 10hp but ideally 15hp i know my raider 18 with 6hp on the back chugs along ok, but i'm pretty sure it would struggle in a heavy sea. That said i think if the sea was that bad and i had a dead main engine it would be enough to keep me nose into the waves whilst waiting for the real help (lifeboat) to arrive, but i hope i plan my trips well enough to avoid any disasters Simon L Quote Link to comment Share on other sites More sharing options...
Newboy Posted August 16, 2006 Report Share Posted August 16, 2006 As Simon said, you really need to get as big as you can afford. Especially if you go out of Poole or Christchurch harbours. The current can be very fast and a 10 horse wouldn't do uch good. Quote Link to comment Share on other sites More sharing options...
duncan Posted August 17, 2006 Report Share Posted August 17, 2006 I fitted a 4hp to my 660 Delquay when I started getting a bit more adventuorus........in tests it could deliver just under 4 knots but was never used in anger. In poor conditions you are looking to be able to make progress in your direction of choice against the wind (if the tides foul then anchor) but if you are looking to fit an auxillary to take you where you want to go when you want to do it then frankly you would be better off with a twin engined boat! Obviously IMO Quote Link to comment Share on other sites More sharing options...
Afishionado Posted August 17, 2006 Report Share Posted August 17, 2006 Once again Duncan and I are in agreement This question of A/ Auxillary or not? or B/ If so how big? has more to it than is obvious at first thought. Can a small auxilliary get you out of big trouble/ bad sea/high wind/strong tide race? NO! it can not to do those jobs the power would certainly need to be 15hp +. Then you would still have the problem of pulling a manual starter, using the throttle (vital in a big sea to prevent a broach) and steering etc. So as Duncan said one would be far far better off with a twin engine set up of 2 X 40hp or whatever. What can a small auxilliary do for you? Basicaly nothing except move you very slowly on a calm sea with little current and hardly any wind. Can you see whare this is going? .......... IMO a small auxilliary is a waste of time on a boat powered by a modern O/B. Modern O/B's are relatively bullet proof but if they fail then one should use a radio or a phone to get help and stick the anchor down and stay put. If the weather is that atrocious then getting a small engine hanging well out over the stern started let alone keeping it going is a bit of a none starter. Mad Mike Quote Link to comment Share on other sites More sharing options...
Newboy Posted August 17, 2006 Report Share Posted August 17, 2006 Mike, I disagree slightly there, yes modern outboard rarely breaks down, but it could be a simple thing like clogged filter or water in fuel etc. Diagnosising it wouldn't be on the top of my agenda in a rough sea and the weather closing in (we all know how weather can change without warning). So I think a suitable back up is advisable whether for practice or just peace of mind. Obivously a twinned engined boat would solve that problem but on smaller boat there just isn't enough space to put 2 engines on the back. Quote Link to comment Share on other sites More sharing options...
Member Removed Posted August 17, 2006 Author Report Share Posted August 17, 2006 ta for the replys. seems like a aux might be a waste of time as i'd need 15hp then i'd have probs with lifting on and off as the boat is moored. main engine is 120hp diesel so should'nt have probs.dave Quote Link to comment Share on other sites More sharing options...
Afishionado Posted August 17, 2006 Report Share Posted August 17, 2006 ta for the replys. seems like a aux might be a waste of time as i'd need 15hp then i'd have probs with lifting on and off as the boat is moored. main engine is 120hp diesel so should'nt have probs.dave Logic prevails Good decision mate Mad Mike Quote Link to comment Share on other sites More sharing options...
duncan Posted August 18, 2006 Report Share Posted August 18, 2006 (edited) if the main engine is a diesel then you have even less benefit from the auxillary OB! How much fuel were you planning to carry and how would you store any volume sufficient to get you home from your furthest point? Without doubt the best all round solution is to carry the appropriate spares for your engine and know how to change/fit them. Alternator belt, raw water impellor, 2 x primary 1x secondary fuel filters plus liquids (fresh water, oil, powersteering fluid, drive oil if on a drive with remote resovoir), some rubber hose repair capability. Carry a tool box. Install engine room lighting or have it available (those fluorecent tubes on long wires are really usefull on a fishing boat anyway and not getting hot are great in enclosed spaces!) Install and maintain a 2 battery system. Keep the fuel clean. Look forward to meeting you out on the water sometime. Edited August 18, 2006 by duncan Quote Link to comment Share on other sites More sharing options...
Mike Fox Posted August 18, 2006 Report Share Posted August 18, 2006 I have moved 2-3 ton of boat into marina berths in the past in calmish conditions with just a 2hb outboard - once rigged on a lifting bracket, the other time using an inflatable dinghy lashed alongside. Best speed attained was 4 knots. A small auxilliary like that will not move you effectively against either wind or tide, but can do the final bit, or take you out of initial danger into somewhere where you can anchor more safely, or maybe pick up a buoy if anchoring close to moorings is unsafe. Many people do choose larger auxilliaries, and picking a model that uses an identical fuel/oil mixture makes more sense. Like many things - it is a compromise. Mike Quote Link to comment Share on other sites More sharing options...
Fugazi Posted August 21, 2006 Report Share Posted August 21, 2006 What can a small auxilliary do for you? Basicaly nothing except move you very slowly on a calm sea with little current and hardly any wind. Can you see whare this is going? .......... It depends, having surfaced from a 38mtr dive last Thursday to find the surface cover dive RIB picking me up using its 4HP auxiliary was infinitely better than a long drift down towards Portland Bill. Yes modern engines are very reliable, but not when someone moving a heavy dive bag snaps the key off flush in the ignition! Although it took 1-1/2 hrs to get back the 6 mile to Kimmeridge in a moderate sea it was better than calling out the rescue services. Any back up is better than nothing at all. Gordon H Quote Link to comment Share on other sites More sharing options...
Paul J Posted August 21, 2006 Report Share Posted August 21, 2006 I can push my 17 ft Whaler ( 1000lbs) with a 4hp and have even got through the run at full tilt but this is a struggle, an 8hp would be better. You have to make sure you can steer and still see where your going, if the throttle can be set without having to hold the tiller then you can steer with your main engine although the leg will create drag. An auxillary must be used regularily or it will probaly fail when you need it most, so use it for trolling or practise using it in a normal situation. It's got to be set low enough or the prop wont stay in the water in a big swell. Fuel mix is an issue, you may have to keep extra if you main engine is not compatible eg: has an oil reserve rather than manual mixing. Im thinking about dropping my auxilary due to my new reliable engine but sods law says as soon a i do, i'll need it. One other bonus is that you can get through very shallow water with just the auxilary running. Lots of pro's and cons- your decision PJ Quote Link to comment Share on other sites More sharing options...
plaicemat Posted August 21, 2006 Report Share Posted August 21, 2006 I have a piece of plastic domestic waste pipe pushed onto the twist-grip throttle on the tiller as an extension to allow me to stand up and operate the throttle. Terry. Quote Link to comment Share on other sites More sharing options...
duncan Posted August 21, 2006 Report Share Posted August 21, 2006 understand adn accept your point Gordon but a spare key and a good tool kit would have solved that problem just as easily - although possibly not fast enough to deal with divers in the water and a tide I agree. Did the aux make it all the way on the fuel in it;s built in tank alone? Quote Link to comment Share on other sites More sharing options...
Newboy Posted August 21, 2006 Report Share Posted August 21, 2006 If the key is snapped off flushed leaving the broken bit inside, I can't see how a spare key and a tool kit is gonna help, unless they also have a drill etc onboard?! Quote Link to comment Share on other sites More sharing options...
duncan Posted August 22, 2006 Report Share Posted August 22, 2006 don't you carry a drill? I find a 24v cordless really usefull onboard. in this instance I would use the dremel with a view to being in a position to either notch the top and bottom of the remaining piece and lever it out (choice 2) or cut a slot in the top of the key to try and turn with a screwdriver (choice 3) Choice 1 would be to use a very thin bladed screwdriver or similar slid in beside the key and then turn it - the key releases the lock so turning the barrel will start the engine. I would probably 'sacrifice' a set of feeler guages, or one blade anyway, as my first try. Choice 4 involves wire and connectors/clips. Quote Link to comment Share on other sites More sharing options...
fritchy Posted August 22, 2006 Report Share Posted August 22, 2006 I went through quite a lot of thought about whether or not to put an aux engine on my Quicksilver 580.... I do not want to have to call out the lifeboat to sort me for something like failed engine/fuel issue etc etc..in extremis I might need them, but would prefer not to bother them for something potentialy avoidable.. in the end I went for two seperately wired batteries, and decided to join SeaStart - (A bit like the AA service) costs over 100 pounds per year but I felt that on balance it was better than the hassle/weight/ maintenance/fuel management issue etc of an auxilliary, but still gives me a (good) feeling that I am taking reasonable steps to avoid an unnecessary RNLI callout. I also have two anchors. I can imagine some scenarios where an aux would be very beneficial, but at the end of the day it is a question of finding the right balance... I would be interested in anyone else/s views on SeaStart. I am pleased to say that so far I have not needed to use them. Cheers, Mike F Quote Link to comment Share on other sites More sharing options...
Fugazi Posted August 22, 2006 Report Share Posted August 22, 2006 Did the aux make it all the way on the fuel in it;s built in tank alone? No, it needed two refills but we carry spare fuel. Still pretty impressive that a 4HP made 4 knots all the way with a 5.25m RIB 4 divers and all their kit on board. Did you know that a snapped off key doesn Quote Link to comment Share on other sites More sharing options...
Brian Posted August 22, 2006 Report Share Posted August 22, 2006 Couldn't you get to the wires behind the switch and "Hot Wire it? Quote Link to comment Share on other sites More sharing options...
duncan Posted August 22, 2006 Report Share Posted August 22, 2006 Don't know Gordon - I have a snapped off key in a cabinet lock here at home and it operates the lock fine with a screwdriver! I can only assume it wasn't all the way in or in some other way misalligned. Quote Link to comment Share on other sites More sharing options...
Fugazi Posted August 22, 2006 Report Share Posted August 22, 2006 Couldn't you get to the wires behind the switch and "Hot Wire it? Brian, Probably, but on the day it was a bit lumpy offshore and dismantling a control box in an open boat with a basic tool kit seemed a tough option when we knew it could be sorted out easily back on shore. Anyway, we now carry a spare key hidden on board, so we Quote Link to comment Share on other sites More sharing options...
Afishionado Posted August 23, 2006 Report Share Posted August 23, 2006 Quote........Still pretty impressive that a 4HP made 4 knots all the way with a 5.25m RIB 4 divers and all their kit on board No it's not ! It is the boat that suports the weight not the engine. As a displacement craft in calmish winds and no current a man powered paddle will move the boat, and several paddles in unison would give maybe 4 knts. A few years ago because of a silly marine tax law the French were taxed heavily if they had an engine in a yacht. At that time most French yachts used a long sweep as a scull to propel the boat. A 30 yacht could be moved easily by a bloke and an oar. (in calm waters with slight wind). Surely the point of all this is not how big or small an auxilliary is it is whether the use of one is practical in all but reasonable conditions. I used to carry one (7.5 Mercury) and the only time I have ever had to use an auxilliary was about 25 years ago when the pull cord broke on the main 50 Merc' one night off Ballard. The 7.5 took two and a half hours to push us back to the slip in Holes bay. At the risk of creating a Jonah like jinx; In 50 years of using small boats with single engines I have only used an auxilliary once. Did I NEED to use it? No, I could have stayed put and begged a tow in the morning. Was it convenient to have it? Yes, I fixed the pull cord overnight and was using the boat the next day. Mad Mike Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.