Originally Posted by spareribs
you wont get a sensible answer on here mate, not one that I would trust , phone up the rnli and ask them, at least its from the horses mouth. You dont know who's who on here. All you'll get is a load of mixed opinions from people who think they are all experts. This site is really an SEO operation for rib related firms. If someone on here has a 5 hp engine for sale , they will say 5hp etc. You get the picture !
Spareribs - why are you hanging about here is its pointless?
Mixed opinions are useful, because very few things in life are absolutely clear cut. With a little intelligence its usually possible to see if someone is pushing a particular agenda, or has an unsubstantiated view which is at odds to the rest of the community. As Anchorhandler says if 85% of people agree its probably a good indication. If you only ask one person at the RNLI you'll only get one answer, doesn't mean its right. Being on the RNLI crew doesn't make you an expert in ribs or boat safety necessarily. Even being an RNLI sea safety adviser (not that I have a problem with them) doesn't mean you have any real practical experience of ribbing in the sort of way you plan to use your boat.
Originally Posted by Gramas
What aux do you think id be best using? Rib is 4.5metres so do i get small 3/4 hp 2 or 4 stroke or an electric with good thrust power, oars or call rnli for tow back in should the main break down???
There is a rule-of-thumb which has been popularised on here which is 1HP per metre of length. Although for practical / space reasons many people will be constrained to using something smaller which might limit their options in strong currents (but still give more control and choice than waiting for a tow!).
Electric is not really feasible for an Aux: only the very expensive torquedo's have an integral battery - and you should assume your main boat battery is part of the problem with the main engine. Even the biggest torquedo isn't going to move a 4.5m rib very fast and will probably not last as long on a single charge as a 4 HP and a 5L can of fuel.
Oars (need rowlocks of some sort) or paddles will be ok in a sheltered harbour but I can't imagine using them to any success with 1m waves even to get 1/2 a mile back to shore. However if 90% of your trips will be in busy areas, or with friends then the aux might be unnecessary - just buy a good tow rope.
The 2 v's 4 stroke question will depend on storage. 4strokes are awkward to store (don't like lying in certain ways) and are often "fatter" on the transom. Do you have space to fit it permanently on the transom and still steer the engine? A frames often get in the way. Do you have space to store it (upright?) elsewhere on board? Can you imagine manhandling it on the transom rolling around in a 1m+ swell? If you are inclined to go wave hopping rather than gentle cruising
A preferred option here for a long aux trip is to set up the aux in a fixed ahead position, set the throttle and then return to the helm to steer using the main engine as a rudder. Beware the main engine will add considerable drag and only provide wide turns but its preferable to siting perched on the tube trying throttle and steer for a couple of hours.