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Old 21 June 2021, 17:20   #1
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Country: UK - Wales
Town: Llantwit Fardre, Pontypri
Boat name: Zodiac
Make: Zodiac Cadet
Length: 3m +
Engine: Evinrude 9.9hp
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Posts: 18
New to SIBing and after some guidance

Hi all,
I bought a Zodiac cadet 310 with an Evinrude 9.9...dating back to 1980's I believe.
We've been out on it about 6 times and love it exploring rivers and a short distance out of river mouths.
The issues I've encountered are as follows
When I go to accelerate the rear end starts to go deeper, the engine sounds like it's struggling and we encountered speed loss, I'm only talking trying to go up to about 10 knots. We've tried moving weight forwards ie the Mrs and dog right at the front along with the anchor and grub etc and me sat on the seat stretching to hold the tiller but without any joy. At low revs it seems to plod through the water okay but just doesn't speed up!
Also we get lots of splashes coming over when we head into any wind/current which the dog loves to bark at persistently...fun at first but annoying after a short time.
Any suggestions please? We just want to have a bit more fun and a tad more speed.
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Old 21 June 2021, 17:34   #2
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Country: UK - England
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Boat name: Nimrod II
Make: Aerotec 380
Length: 3m +
Engine: Tohatsu 9.8 2-stroke
Join Date: Nov 2007
Posts: 6,741
Hello and welcome to the forum.

Regarding the boat are you sure it is 100% up to pressure using an accurate gauge? You seem to be trying to get the weight distribution right which is important.

No disrespect intended but I'm assuming you are both around average weight... makes a big difference with smaller sibs and OBs.

Do you believe the outboard is developing full power and the throttle opening fully to reach maximum revs? Do you know what the prop pitch is... too great a pitch will hamper getting over the hump and on the plane... I would guess you should have an 8" or 9" max.

If you have hit 10kts you must be on the plane.

Just a few thoughts to start as this outfit should plane OK to about 14/15kts.
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Old 21 June 2021, 17:46   #3
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Country: UK - England
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Make: Jago
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Also, in addition to Fenlanders good advice, check what position your trim pin is in.
Also, as I just found out, those evinrude have a shallow water position which would stick the bow in the air if given the beans.
Certainly should plane fairly easily if set up correctly.
Mine planes ok (just) with me and the boy with a 6hp Chinese motor so with nearly double that you should be OK.
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Old 21 June 2021, 17:58   #4
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Ahh yes good call... forgot the OB trim itself.
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Old 21 June 2021, 19:09   #5
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Country: UK - Wales
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Posts: 18
I've tried moving the trim position and found that the further away it goes the bigger the issue so I last used it without the pin in which made it marginally better but not a lot, my other half is pretty slender whilst I'm on the larger size and the dogs quite small but loud! Regarding the pressure I'm hoping to pick up a Bravo BTP digital pump later this week, as I've read that this is a good reliable pump although it comes with a tasty price tag. I'm not sure about the degrees of pitch is or how to measure it. Reading other posts I'm also wondering if my foil thingy above the prop is low in the water? Sits a few inches under the water level?
The engine tries to give more power but it just doesn't relate to increased speed yet.
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Old 22 June 2021, 01:10   #6
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Country: UK - England
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Maybe its a long shaft engine on a short shaft boat?
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Old 22 June 2021, 01:33   #7
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Nothing worse than an incessant yapper but even the smallest dogs can be reprogrammed. I'm guessing yours will yap in other situations at home? Just focus for a month or so on making it sit and face you when it starts a yapping episode and giving it a reward for keeping its mouth closed. It can be a lot of work but you then get a lifetime of hassle free behaviour.

Re the boat, if the engine is healthy, then it's probably weight distribution or Hull pressure. You could further test the former by asking the skinny member of the crew to helm to free up the pie connoisseur to apply their superior ballast skills closer to the bow as well as double checking pressures with an additional gauge.

If the engine is particularly old, what have you done to assure yourself that it's putting out good power? As Fendlander also mooted, it has to be worth checking the prop spec in case during its long life it had been changed by someone away from factory.

But definitely start reprogramming the dog today as incessant yapping will drive anyone insane and will suck the pleasure from days out once you've sorted the boat.
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Old 22 June 2021, 04:08   #8
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Ha ha not keen on a yappy dog TmM? Our new pup we had at 8wks is known to be of a yappy breed so we work hard to provide guidance and environment where this issue is largely removed. He now barks about three times when the doorbell goes but stops and stands quietly the moment we take over door guarding by opening it. If left shut out in the garden he barks just once to come in then waits for the door to be opened. On a walk he doesn't bark at any dogs, cats, people, cars, bikes etc. Most crucial when the three young grandchildren are next door in the huge paddling pool next to the fence yapping at the top of their voices there's not a murmur from him... thank goodness. At six months old now we are very pleased with this progress.

I was amused at your weight swapping description. I have been know to previously refer to Mrs F as moveable ballast but for comfort lately she has become fixed ballast on the seat of the Aerotec. The Elling however has sliding seat positions so that will make it easier to get her positioning spot on.
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Old 22 June 2021, 12:11   #9
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I'm yet to get out on the water with the new SIB. It does mildly concern me that as a pie connoisseur for many years but with two skinny children it might be a little interesting getting the boat balanced.

I genuinely don't know how someone can stay sane if a dog is barking all day, let alone understand how the dog can keep it up for so long.

Tim.
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Old 22 June 2021, 13:40   #10
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RIBase
What is the prop size?
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Old 22 June 2021, 13:54   #11
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I'm not sure to be truthful, how and where do you measure it from and to? Or should it be stamped on it somewhere?
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Old 22 June 2021, 14:42   #12
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Yes always a stamp either dia and pitch or a part no you can Google.
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Old 22 June 2021, 15:03   #13
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Inside the prop it says 10 x 9 does this make sense?
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Old 22 June 2021, 15:13   #14
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Sounds a bit big to me both on diameter and pitch.
I will check what is fitted to mine tomorrow but it will be weekend before I get it in the water and see if it's propped correctly.
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Old 22 June 2021, 16:17   #15
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Thanks Wazzajnr
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Old 22 June 2021, 16:55   #16
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Just had a look online and it seems standard diameter should be 9 1/4" and yours is 10".
Pitch is recommended anything from 7 to 12 and yours is 10.
I would suggest buying a "tinytach" off amazon or ebay and see what rpm the engine is running at on the boat with throttle wide open.
That will give you far more info. The 9.9hp from memory WOT range is 4500 to 5000 which is relatively low so if its propped incorrectly you will never get into that range and it will be bogged all the time.
If you're anywhere near Anglesey this weekend, I'll be trying out my "new to me" evinrude 9.9 so would be happy to chuck it on your boat and see if it performs any different. That said, I've no idea how it will run on mine yet! ��
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Old 22 June 2021, 16:58   #17
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https://www.amazon.co.uk/dp/B0756VGD...ing=UTF8&psc=1
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Old 22 June 2021, 17:38   #18
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Agree with Wazza that you should have a 9.25" dia as a standard fit. A 10" dia would usually only be seen on a 9.9hp in a very low pitch like 5" or 6" to move a slow displacement speed boat. The effect of a 10" dia on your outfit will be to add drag and have a similar effect to a pitch size or two up.

A 9" pitch could just be OK in a 9.25 dia but is more suited to a 15hp. From my experiences with similar motor and SIB sizes I'd get a 9.25 x 8" pitch to give the best chance of decent performance.

Like this one assuming it has the correct amount of splines and is the correct fit. I assume you have a thru hub exhaust?

https://www.amazon.co.uk/Flish-Prope...sports&sr=1-11
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Old 23 June 2021, 01:07   #19
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Country: UK - Wales
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Make: Zodiac Cadet
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Engine: Evinrude 9.9hp
Join Date: Jun 2021
Posts: 18
Thanks for the invite and offer Wazza but I'm in South Wales and Anglesey, although beautiful, is a tad far away for a day trip.
I've a good few things to check and adjust following all your advice which I'll get onto and let you know how I get on shortly.
Much appreciated everyone.
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Old 23 June 2021, 03:13   #20
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Ok just checked my two motors.

6hp chinesium special has a 7.8"x8" prop and will just about get on plane 1 up on my 3.2m sib. But the top speed isn't great.

New to me evinrude 9.9 is fitted with a 9.25x8 so I suspect it will jump up on plane much easier but the top speed won't be much better.
It was fitted to a river boat previously so I'm guessing I'll probably have to up the pitch for better top speed.
I'll update after trials this weekend.
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