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  1. #11
    Join Date
    May 2016
    Posts
    153

    Default Re: Small Rib advice

    Any way of determining engine revs at WOT? Prop may not be letting the engine get into it power band - common enough issue for small RIB's and SIB's. I have an old Zodiac 3.1 with 8hp Honda and that does 18kts with two people so I'd imagine a much lighter RIB and engine combo should plane. Also, put the fuel tank up the bow, every little bit helps.

  2. #12
    Join Date
    May 2001
    Posts
    15,587

    Default Re: Small Rib advice

    Quote Originally Posted by Greg2 View Post
    Whilst I stand to be corrected I would be surprised if a 2.6m RIB fitted with a 5hp engine manages to get on the plane properly with a 17st bloke in it no matter where you sit. I am a similar size and have had several RIBs in the 2.7 to 3.1m bracket (hulls in GRP, ali and airdeck) and have always had a 10hp to get any kind of decent performance. It sounds to me like it is not getting fully on the plane and a larger motor may well flatten things out as the stern lifts properly onto the plane.
    Thatís what I was thinking. I have an Avon 2.8 with a 15hp, with just 2 of us it takes a bit of effort to plane.

    I just think 5hp is not enough.

  3. #13
    Join Date
    Dec 2001
    Location
    north ayrshire
    Posts
    478

    Default Re: Small Rib advice

    We have a 2.8 aluminium hull tender it planes fine with 2 adults and a 3 year oldwith an 8hp, it previously had a 5hp yam 2 stroke and it would plane with 1 adult and child even with a 17 stone passenger it should plane although I'd admit it is on the limit. maybe a set of dole fins would give it the little extra lift in the stern it needs

  4. #14
    Join Date
    Mar 2016
    Posts
    1,026

    Default Re: Small Rib advice

    Not sure where that advice on engine set up came from but itís wrong.

    Anyway. Iím thinking that maybe your new rib is shorter than the old ? Shorter hulls do this.
    I had a 3m valiant rib that would plane easily with 2 onboard and an 8hp Yam 2 stroke.
    The same engine on a 2.7m brigg and 2 onboard wouldnít plane. Despite being lighter.

  5. #15
    Join Date
    Jan 2013
    Location
    Guernsey
    Posts
    386

    Default Re: Small Rib advice

    I had a 2.3 rib from Tohatsu with a 15hp Yam. The bow stood up so far I used to stand right at the bow, holding the painter, with a long tiller extention and kill cord.

    After bombing around Herm and Sark like this, decided to fit a pair of dolphin fins to the trim plate. Cheap, simple and made all the difference.
    Dolphin fins.jpg

  6. #16
    Join Date
    Jun 2012
    Posts
    77

    Default Re: Small Rib advice

    Iíve got 2.7 walker bay rib with 5hp mercury 2 stroke and that planes and Iím 14stone 6 lbs

  7. #17
    Join Date
    Feb 2016
    Location
    Western Australia
    Posts
    204

    Default Re: Small Rib advice

    Quote Originally Posted by Rocksteadee View Post
    Could you get someone to video you?
    If you have Navionics on your phone, thus can give you your speed. I would guess that you would have to be about 8 it’s to be planing.
    A tiller extension would help to get weight further forward
    I thought about a tiller extension but thought I would add the family first - just have to wait for that to happen.. I should be able to get speed no problem. It felt faster than 8 kts.

    Quote Originally Posted by Beamishken View Post
    The usual method of lifting a clamp on engine is to sit the engine on a wood batten the required thickness laid along the top of the transom. Obviously you can only go up around 25 or 30mm before you run out of space for the clamps to grip but thats often enough.
    The tel tail sign of the engine being too low are lots of spray shooting off to each side or upwards to the power head or the av plate being completely buried when on the plane.
    I have measured the engine / hull - hull is for short shaft - which is what it is.. so transom is approx 410mm (directly along it) to the keel bottom (only small) and the engine is about 435mm to bottom of cav plate. A small lift may make a difference but I'll need to remove the clamp pads etc to block it up.

    Quote Originally Posted by Greg2 View Post
    Whilst I stand to be corrected I would be surprised if a 2.6m RIB fitted with a 5hp engine manages to get on the plane properly with a 17st bloke in it no matter where you sit. I am a similar size and have had several RIBs in the 2.7 to 3.1m bracket (hulls in GRP, ali and airdeck) and have always had a 10hp to get any kind of decent performance. It sounds to me like it is not getting fully on the plane and a larger motor may well flatten things out as the stern lifts properly onto the plane.
    You could well be right.. but it felt like it was trying - motor isnt run in yet.. (not even used one tank) so being a bit careful but it felt like it wasnt struggling - the RIB is only rated to 5hp.. as its only a 2.6m..

    Quote Originally Posted by Ferris View Post
    Any way of determining engine revs at WOT? Prop may not be letting the engine get into it power band - common enough issue for small RIB's and SIB's. I have an old Zodiac 3.1 with 8hp Honda and that does 18kts with two people so I'd imagine a much lighter RIB and engine combo should plane. Also, put the fuel tank up the bow, every little bit helps.
    I'm looking at adding an inductive tach.. cheap and easy.. so should be able to sort something out. Fuel tank is 2.5ls and is in the engine cowling..

    Quote Originally Posted by longjohnsilver View Post
    That’s what I was thinking. I have an Avon 2.8 with a 15hp, with just 2 of us it takes a bit of effort to plane.

    I just think 5hp is not enough.
    Thanks - that is what I am trying to find out. I assume the avon is soft bottomed? also a bit more than 30kg?

    Quote Originally Posted by Beamishken View Post
    We have a 2.8 aluminium hull tender it planes fine with 2 adults and a 3 year oldwith an 8hp, it previously had a 5hp yam 2 stroke and it would plane with 1 adult and child even with a 17 stone passenger it should plane although I'd admit it is on the limit. maybe a set of dole fins would give it the little extra lift in the stern it needs
    Thanks - I'm looking at the fins as an option - just want to ensure i'm covering all bases.

    Quote Originally Posted by QBhoy View Post
    Not sure where that advice on engine set up came from but it’s wrong.

    Anyway. I’m thinking that maybe your new rib is shorter than the old ? Shorter hulls do this.
    I had a 3m valiant rib that would plane easily with 2 onboard and an 8hp Yam 2 stroke.
    The same engine on a 2.7m brigg and 2 onboard wouldn’t plane. Despite being lighter.
    Old rib and new are same - old rib had a 2.5hp 4 stroke - and that wouldnt plane.. very sedate - the rib was over 50kg too.. and a lot flatter hull than the new..

    Quote Originally Posted by Fishtigua View Post
    I had a 2.3 rib from Tohatsu with a 15hp Yam. The bow stood up so far I used to stand right at the bow, holding the painter, with a long tiller extention and kill cord.

    After bombing around Herm and Sark like this, decided to fit a pair of dolphin fins to the trim plate. Cheap, simple and made all the difference.
    Dolphin fins.jpg
    wow - 2.3m rib with a 15hp.. sounds like fun.. yep looking at the fins once I know I have covered all bases..

    Quote Originally Posted by Restoration man View Post
    I’ve got 2.7 walker bay rib with 5hp mercury 2 stroke and that planes and I’m 14stone 6 lbs
    Good to know.. what weight is the rib and what hull?

    So I have the measurements so it looks like the engine is probably low but marginal.

    While cleaning its is noticeable how much higher at the front it is that the old zodiac - so it could also be me not being used to it and thinking its high bow running when in fact its just the tubes being high at the front. I'll try and get some pictures over the next few days of the hull and boat in general.

    Will update soon

    Steve

  8. #18
    Join Date
    Nov 2013
    Posts
    67

    Default Re: Small Rib advice

    Ive got exactly the same problem bought 2.9 Quicksilver Ali Lightweight hull for a tender as we beach a lot and we have massive tides here in the Bristol Channel hard work dragging anything back to the sea !

    Boat plate clearly states 15Hp max so to be sure we purchased 10Hp - 43Kg well inside max 50Kg

    Beach wheel fitted to the transom small grey ones, Im a large lad 16.5 stone and when I need to start engine etc my weight on the stern makes it so unsafe I can see it flipping backwards.

    If i sit in the bow and my son operated it flies planes early etc but one person no chance!

    Moved fuel tank up front etc just little peeved as I have a 4hp engine but wanted to have some fun in it?

    Stuck between choices?? any advice to help it get up on plane with 10hp and crack on a bit appreciated.

    Or have I been miss sold this engine rib comb?

    Love the rib its great build quality etc

    I have a sea-rider with a 115hp that flies but wont fit in the Targas Garage!!!

    TIA!

  9. #19
    Join Date
    May 2001
    Posts
    15,587

    Default Re: Small Rib advice

    No the Avon is a grp rib.

  10. #20
    Join Date
    Jun 2001
    Location
    Belgium
    Posts
    455

    Default Re: Small Rib advice

    Quote Originally Posted by Lulla-Belle View Post
    Ive got exactly the same problem bought 2.9 Quicksilver Ali Lightweight hull for a tender as we beach a lot and we have massive tides here in the Bristol Channel hard work dragging anything back to the sea !

    Boat plate clearly states 15Hp max so to be sure we purchased 10Hp - 43Kg well inside max 50Kg

    Beach wheel fitted to the transom small grey ones, Im a large lad 16.5 stone and when I need to start engine etc my weight on the stern makes it so unsafe I can see it flipping backwards.

    If i sit in the bow and my son operated it flies planes early etc but one person no chance!

    Moved fuel tank up front etc just little peeved as I have a 4hp engine but wanted to have some fun in it?

    Stuck between choices?? any advice to help it get up on plane with 10hp and crack on a bit appreciated.

    Or have I been miss sold this engine rib comb?

    Love the rib its great build quality etc

    I have a sea-rider with a 115hp that flies but wont fit in the Targas Garage!!!

    TIA!
    Lulla-Belle do you have the Targa 52? . Would be interested to know if the a 290 rib fits with it's engine on? Also looking for a small rib in the T52

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