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Old 06 July 2016, 14:00   #1
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Need Help Deciding on What RIB to Purchase, and How to Outfit It

Hey all,

I decided to sell my Cadet 350 and Mercury 15 motor, the pain of re-assembling and disassembling the boat every time was too much of a hassle.

Given that, I'm keen on upgrading to a RIB before next summer hits. I'm hoping for knowledgeable suggestions on what I should be looking for.

When it comes right down to it, I want a boat that's going to have sporty performance characteristics and be a blast to run around in. Moderately fast (40mph+), nimble, and sturdy/stable are what I'm after.

As far as size, I think around 5 to 5.5 meters is the sweet spot. I'd like to be able to comfortably seat at least 4-5 adults (including the Captain).

My research thusfar has led me to be seriously looking at the Zodiac Bayrunner series. What concerns me about these boats are the seats, especially on the 550 which lacks the handholds, they just don't appear to be "secure" feeling at higher speeds on choppy waters. Granted, I could have a bare hull outfitted to a similar layout with better seats, but I wouldn't have a clue as to what would fit or look/feel superior to the stock seats. What would be super-nice is a bench seat at the helm which could switch between being a seat, and a nice bolster for stand-up operation.

Another concern about the Bayrunner is how to power it. The Mercury 75, 90, and 115 HP four-strokes all weigh the same and use the exact same chassis. I know that if I bought a 500 hull I would really want to power it with a 90 (20HP over the 70HP stated), and the 550 with a 115HP (25HP over stated). Would slightly "overpowering" the boat in this manner create a significant structural integrity risk? I'm not certain if the stated HP is determined by what Zodiac thinks a given outboard weighs so that it doesn't overload the transom, or by some function of how much power they deem is "safe".

Anyway, knowledgeable input from experienced RIB operators is more than welcome
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Old 06 July 2016, 16:40   #2
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I suppose it's not just based on weight. The power is the killer, think of the outboard as a lever/ fulcrum. The more power you put behind that lever the more strain on the transom. Kinda like pulling nails with a hammer.
I could be very wrong I suppose someone else knows better.
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Old 06 July 2016, 21:40   #3
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Well for a start Yamaha and zodiac have done performance testing on these models. That can be found on the Yamaha outboard website under owner resources. That will give you an idea of the speeds with the power packages that Zodiac offers them with. Second the HP ratings are not determined by the manufacturers alone unless it is a boat that is not built to coast guard or National marine manufacturers standards. This is why you see simiLar horsepower ratings on similar sized boats between brands such as Zodiac, Novurania, and AB.
Overloading in many cases is not only dangerous but highly illegal and in some states the fines are outrageous. I know someone who learned the hard way.
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Old 07 July 2016, 03:12   #4
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Quote:
Originally Posted by kestrel452 View Post
... Moderately fast (40mph+), nimble, and sturdy/stable are what I'm after...

...My research thusfar has led me to be seriously looking at the Zodiac Bayrunner series...

...What concerns me about these boats are the seats, especially on the 550 which lacks the handholds, they just don't appear to be "secure" feeling at higher speeds on choppy waters...

... I know that if I bought a 500 hull I would really want to power it with a 90 (20HP over the 70HP stated), and the 550 with a 115HP (25HP over stated). Would slightly "overpowering" the boat in this manner create a significant structural integrity risk?...
If you want to run a fast rib in chop with passengers then I think sideways facing bench seats at the front are probably the worst possible design.



There's no way I'd be sitting on there at 40 knots.

I've no idea why you'd want to overpower it before you've even tried it, giving you warranty issues. Zodiac know that HP is not = weight.
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Old 07 July 2016, 03:51   #5
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Boat manufacturers usually give a maximum recommended engine size.
Seeing that you are in the land of the litigator if you exceed that recommendation & have an incident I could see your insurers - if you find one that will take it on in the first place - dumping you in a hurry & leaving you to foot the bill.
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Old 07 July 2016, 08:00   #6
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stick a 90 on 5.5 you'll get 40 + mph set up properly in flat conditions if its rough your arse will tell you to slow down before your brain does
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Old 07 July 2016, 08:20   #7
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The Bayrunner 550 with a Mercury 90hp is a 48 mph boat...it's a little faster than the Yamaha thanks to the displacement. If you want to squeeze out a little more horsepower, the Pro Open 550 is rated for a 115. It's a stiffer hull layout with bigger tubes though.

HP rating is determined by the size of the boat as well as the whether or not the boat can maneuver safely at top speed. Tube size has a lot to do with it, since the tubes are the heart of the boat's buoyancy. With a larger tube diameter, the end cones are bigger, which means more buoyancy around the stern.

The Bayrunnner is exactly that...it's designed to run around a bay. Sure, you can take it out in the rougher stuff, but it really is not designed for it.

The models that are more "offshore" oriented are the RecPros and the Pro Opens.
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Old 07 July 2016, 08:50   #8
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I hear all of you on the overpower aspect, most mechanics I called yesterday to ask if they thought it'd pose an issue said they wouldn't rig anything above what the plate said anyway. They wouldn't even put a Merc 75 (only 5 horses over), which is disappointing since Mercury doesn't make a 70 and they're what most shops service around here.

What's the top speed difference between a Bayrunner 500 and 550 when rigged to the max stated HP? From what people are saying in this thread, and what dealers have told me as well, the 550 should be doing 40-45mph. Does anyone have a decent idea of what speed the 500 will run at with a 70HP engine on the back?

What Poly said about the benches being poorly laid out for faster cruising is exactly what worried me in the first place about the 550. My presumption is it's a slightly faster craft than the 500, but what's the point of paying the extra over the 500 if the 550 is going to be much less secure feeling at speed? Does anyone possibly have suggestions on how to custom outfit a 550 hull seating-wise to make higher speed operation more comfortable, and with what seats?
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Old 07 July 2016, 09:01   #9
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shock-mitigation seats are the way to go jockey seats as a minimum if you want to tear around or standing with a bolster seat adjustable back rest.but shock seats are great
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Old 07 July 2016, 09:02   #10
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Quote:
Originally Posted by kestrel452 View Post
I hear all of you on the overpower aspect, most mechanics I called yesterday to ask if they thought it'd pose an issue said they wouldn't rig anything above what the plate said anyway. They wouldn't even put a Merc 75 (only 5 horses over), which is disappointing since Mercury doesn't make a 70 and they're what most shops service around here.

What's the top speed difference between a Bayrunner 500 and 550 when rigged to the max stated HP? From what people are saying in this thread, and what dealers have told me as well, the 550 should be doing 40-45mph. Does anyone have a decent idea of what speed the 500 will run at with a 70HP engine on the back?

What Poly said about the benches being poorly laid out for faster cruising is exactly what worried me in the first place about the 550. My presumption is it's a slightly faster craft than the 500, but what's the point of paying the extra over the 500 if the 550 is going to be much less secure feeling at speed? Does anyone possibly have suggestions on how to custom outfit a 550 hull seating-wise to make higher speed operation more comfortable, and with what seats?
The 550 has a large integral fuel tank.
The 500 does not (you'll have to use a big red portable fuel tank).
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