Advice on Re-powering Zodiac Pro 550 Rib

[cornishcoote]

Your views please.

I have a Zodiac 5.5m Pro 550 Rib with a 2005 Honda 75 hp outboard which so far has been excellent in terms of reliably. However, the boat is underpowered to the point I always feel guilty that I am 'ringing it's neck'. I seem to need to be in the top last 1000rpm where ever I go. On a good day I can currently get 32mph flat out. Reality is I have to cruise at 22mph or so.

So I made the mistake of phoning a local marine dealer enquiring about whether bigger used honda outboards ever come up.

The dealer said it was unlikely and advised it was a bit of a step into the unknown in terms of reliability etc.

He then mentioned he could do a massive discount on a new Mariner 115hp ( max for my boat).

The benefits I can see is :

Better cruising speed say 35mph but at a more economical rpm
More range?
5yr warranty
Same weight as my current outboard
Quieter


Basically is it worth it? Cost vs benefits vs current value of my boat etc?
Or later upgrade boat and engine?

I am also worried as I heard about this chine walk problem?

Or am I just being a stupid and jealous that my Rib is so much slower than my mates!!! And should stick with what I got [emoji53]

Any thoughts appeciated.

[jonp]

Like you I feel my pro 550 ( 2014 tour ighter model ) is under gunned, especially in calm water. I'm running a yam f70 4 stroke with a 14 pitch prop which gets me out to 6000rpm for about 32knots flat out.

I've owned both the Suzuki and Honda 90 on other boats and feel either of these would be perfect for my boat. Over here suzukis are cheaper to buy and run than the Honda when you look at spares and initial cost.

Yamaha have a new 90 4 stroke I'm hoping to get a deal on with a decent exchange but if the figures don't seem to good I will continue to run the Yam 70 in the 4700- 5200 rpm range.

Basically the deal you mention comes down to how much you use your boat, if you have the weather and opportunity to spend lots of time out enjoying it, then it's no issue.


Jon

[office888]

Pro 550 is only rated for 90hp. Unless you have a Pro Open 550?

In either case, I'm running a 5.6m Avon with a Mercury 115hp Command Thrust (low ratio lower unit), Spitfire aluminum 14x23 prop. ~45 mph @ 5400 rpm, then it started to chine walk. My ~30-35 mph cruise is right around 3500 rpm or so.

[JTURNER]

I have a 2009 Pro Open 550 with 100hp 2009 Suzuki. I am very pleased with both boat and engine. I tested a 2008 Pro Open 550 running a high hour Yamaha 90HP before I bought this one and I felt that whilst she went up on the plane quickly enough it was just a little underpowered in comparison to the 100hp. I have used my Zodiac Pro Open 550 in the west of Ireland in big rollers and flat calm of the shannon estuary and also in the solent in the flat and peaky chop and have not noticed the chinewalk mentioned by others on the 550. The challenge you may have buying a new engine is that when it comes to resale you may not get full value when selling with the older boat and newer engine. As such if you are going to keep the boat and are happy with it and its overall condition etc then I would consider getting the new engine, if you are going to think about getting a newer boat in the next few years I would sell both boat and engine now and try and get a deal on a 2016 stock boat from one of the UK agents or drive a hard deal with another retailer for a used model with a matched year boat and engine. I have heard good things about the Mercury engines recently - I had a 220HP Mercruiser and also Mercury outboards in the past which where so so in terms of reliability (the smaller 2 stroke outboards are bullet proof) but the new large outboards are meant to be solid and very reliable. 115hp would be pretty powerful on a 550 Pro Open, I personally think 100hp will do you fine and maybe try and negotiate a better deal with the vendor. Good luck JT

[cornishcoote]

Thanks for the replies.

It is the Pro Open 550 model and we do get plenty of use which is nice, even the odd winters day 😀

It's just the cost. New mariner could be around 6,400 plus vat plus fitting. Minus what I can get back on the current Honda outboard.



If I can get a similar cruising speed to what you mentioned then that would be perfect.

[cornishcoote]

Originally Posted by JTURNER

I have a 2009 Pro Open 550 with 100hp 2009 Suzuki. I am very pleased with both boat and engine. I tested a 2008 Pro Open 550 running a high hour Yamaha 90HP before I bought this one and I felt that whilst she went up on the plane quickly enough it was just a little underpowered in comparison to the 100hp. I have used my Zodiac Pro Open 550 in the west of Ireland in big rollers and flat calm of the shannon estuary and also in the solent in the flat and peaky chop and have not noticed the chinewalk mentioned by others on the 550. The challenge you may have buying a new engine is that when it comes to resale you may not get full value when selling with the older boat and newer engine. As such if you are going to keep the boat and are happy with it and its overall condition etc then I would consider getting the new engine, if you are going to think about getting a newer boat in the next few years I would sell both boat and engine now and try and get a deal on a 2016 stock boat from one of the UK agents or drive a hard deal with another retailer for a used model with a matched year boat and engine. I have heard good things about the Mercury engines recently - I had a 220HP Mercruiser and also Mercury outboards in the past which where so so in terms of reliability (the smaller 2 stroke outboards are bullet proof) but the new large outboards are meant to be solid and very reliable. 115hp would be pretty powerful on a 550 Pro Open, I personally think 100hp will do you fine and maybe try and negotiate a better deal with the vendor. Good luck JT

Thanks for this and good to get some real life comparisons. Out of interest what sort of speeds do you get from your 100hp. As you say I'm sure I will save a few bob.

The boat is a bit older, but well cared for and we do love it's size and storage, but will probably only keep a few more years tbh. I guess the left over warranty will appeal, but my concern is potentially loosing all that money.
I would like a bigger rib, but I mostly beach launch it and think the extra weight would be pushing it.

[JTURNER]

Originally Posted by cornishcoote

Thanks for this and good to get some real life comparisons. Out of interest what sort of speeds do you get from your 100hp. As you say I'm sure I will save a few bob.

The boat is a bit older, but well cared for and we do love it's size and storage, but will probably only keep a few more years tbh. I guess the left over warranty will appeal, but my concern is potentially loosing all that money.
I would like a bigger rib, but I mostly beach launch it and think the extra weight would be pushing it.

At WOT I will get 45-46mph which is pretty quick (Suzuki Speedo is in mph) howeve I cruise happily 20-28mph at around 2800-3400 which is easy enough on fuel, just depends on how loaded the boat is. I dont push the boat at all to be honest (kids a bit young for that, but I did test it in the estuary this summer so see what top speed I would get and at WOT its pretty damn quick! This will also depend on the pitch on the prop and I have a few dings in mine which will also impact top speed and revs. Hope that helps. JT

[breezeblock]

Ive got the older 2014 mariner 115 on my humber as when I was buying it the Honda 75 that I had from my previous boat I was told it was going to be as flat as a fart I managed to get the Honda sold for £3500 that was for a pretty mint engine with 200 hrs on it so there is still pretty good money to be gotten from them I would have kept it as I quite like honda stuff .on my humber it does 40/41knots and then it starts to chine walk but to be fair its fast enough I think any more would be uncontrollable the honda on the brig would do from memory 32knots I think.i would say that 100hp on that size of boat is pretty well matched

[cornishcoote]

Thanks for all your advice on this.

Well I just sold my Honda 75hp and got a newer, but second hand, Mariner 100hp fitted today.

So I took it straight out for a sea trial today and the engine sounds great and plenty of power. However the 17" prop needs changing. I'm hitting the 6k rev limit quickly and easily at 37mph. It feels like its got plenty left. Any advice on this?Thinking of 19" ?

Another more concerning point was it doing the dreaded chine walk. Spoke back to the guy who fitted and he said raise it up one hole on the transom? Another thoughts?

I noticed my tubes were a bit low on pressure would this make a difference?

Any advice on what transom height and prop other zodiac Pro open 550 are using?

Thanks

[wellhouse]

not sure what age your honda was but looks like 165kg versus 180kg (4 stroke?). minimal weight difference, what you should be looking for is av plate height dry versus on the move. (see below)
The Outboard Expert: Boost Speed with Outboard Engine Height Adjustments - boats.com
and

https://www.youtube.com/watch?v=_Pb5cGHikwc

once you've got the engine height right and prop'd to make sure you don't over rev, make sure you trim the engine down enough to avoid chine walking. I'm not sure how you had your engine trimmed at the time, but i have a 115 on a 550 open pro and never had chine walking. I can only assume it's a combination of engine position and trim on yours? You've got a lot more power now so a bit of time setting up the engine versus rib will be a worthwhile exercise.

Have you got a long shaft or xl? I've got a 20inch long shaft on mine, 2 stroke so with a tank of oil about 180kg so similar weight wise to yours. I will take some pics of av plate position versus hull bottom later when i get down to the rib. (might help?). I don't think tube pressure will have made a difference to chine walk, the rib hydrodynamics are a function mainly of the hull shape to the water on the plane. On the 550 open pro the front 2/3rds of the tubes are out of the water and the back of the tubes are flat ended (not cone shaped) on the plane. I've not noticed any difference between a cold morning start (tubes on the lower pressure side and later in the day when the sun is up and the tubes are hard).

[Andy_Rs600]

Originally Posted by cornishcoote

Another more concerning point was it doing the dreaded chine walk. Spoke back to the guy who fitted and he said raise it up one hole on the transom? Another thoughts?

Generally the boat is starting to chine walk because it's running too much bow-up, shortening the wetted length. Moving the engine up will mean you have slightly less trim authority (i.e less bow up for any ammount of engine movement) but that's not really a direct solution. The answer is don't trim up quite so much at high throttle settings, and/or add more weight to the bow (or the boat overall). In the right conditions anything with a high power-length ratio can be persuaded to chine walk.

[Phil M]

I have a 530 Pro (1988 vintage) with a new Mercury 115 that's been on for about 18 months. It is an excellent engine. Very quiet even at full chat, fairly frugal and very light for the power (less than a 115 opti). I get about 41mph on full throttle and just over 5200rpm with a 17" prop, so with a change could give a little extra. Hole shot is fantastic and I generally burn about 1.3kn per litre. I've had no chine walk issues but my hull is almost a trimaran (really large reverse chines) which keeps it stable but adds drag. I paid the extra and got the smartcraft gauge upgrade, which i'm very happy with as it gives a lot more monitoring on the gauges and more engine sensors, plus will link to fuel gauge and gps to give you expected fuel range. Fitting was quite easy, for the engine at least although some of the additional sensors needed careful thought as the instructions weren't great.

Hope this helps,

Phil M

[cornishcoote]

Thanks for this.
So it's a 20" long shaft outboard.

I've just been and chatted to my local marine mechanic and he has leant me a 19" prop. He will also let me use his hoist to raise it if need be.

I noticed that the trim was a lot more sensitive compared to my last engine which may indicate it's a bit low?

Wellhouse. Your bang on with the weight. I went from 168kg to 180 kg with the new engine.

[cornishcoote]

Bit of an update after another sea trial today.

I decided to raise the engine up one hole this time and ensured the rib tube pressures were good before testing again.

I had the 19" s/steel prop fitted this time and all seemed good. Got up to 42mph (gps) and although, when flat out, it still had a bit of chine walk, this could now be trimmed out. She then settled well.

Might try a 21" prop as was still going just a smudge over the 6k rev limit, but I did have a light load. Hole shot was awesome.

Thanks for all your advice.