Fitting bigger outboard than Max recommended.

nigel52 · 25 August 2013, 16:43

This question is more longer term but would be interested in people's views.

I have a Piranha 6.0m RIB with a 90hp ETEC. Both are just 1yr old. I am happy with both for the type of RIB cruising we do. However, we have been doing some wakeboarding, waterskiing and may progress to mono-skiing. This configuration is fine for wakeboarding and ok for twin ski water skiing but I think serious mono-skiing is too much for a 90 ETEC and the 115 ETEC would be much better in that one would not be pushing the engine so hard. Most likely the 115hp would be more economical.

Here is my dilemma: My Polish build Piranha 6.0m is rated to a maximum 90HP only; also this RIB requires an extra long shaft ie 25". I rang up Powertech the Evinrude dealer who supplied the engine to enquire about a trade-in to put a 115 ETEC on the RIB but he said he was not allowed to exceed the maximum quoted HP. My reasoning was that the 115HP ETEC is still lighter than other 90HP outboards and it should not be too much of an issue. I also spoke to Piranha and their response was as follows:

"All of our new models are now manufactured with long shafts (20") rather than extra long (25"). Your model is an 25" and yes this may loose a few knts in top speed because of the larger gear box.

We are not at a stage yet where we have CE approval for rigging the 6m with a larger engine and therefore we could certainly not endorse you rigging the 6m with a 115hp."

My question is: If I did decide to uprate the engine would another dealer do the upgrade or do I just bite the bullet and stay with what I have or eventually look at selling current set up and starting again? (I do like the design of the Piranha RIB and ours is in immaculate condition with 4 yrs of warranty left on both boat and RIB)

A final complication is that the boat/engine/trailer are all in France where it is kept and would mean bringing it all back to the UK for the Winter to do the necessary deals.

A1an · 25 August 2013, 16:51

I would think that your remaining warranty won't be worth the paper it's written on should you decided to exceed the Max HP.

whisper · 25 August 2013, 17:02

When a rib is made for resale then it goes through a process and is given a CE approval for a maximum HP.

If you exceed this approved hp rating then I cant see you being insured and you are also knowingly fitting a larger hp engine than is safely recommended for your craft.

Therefore, if something goes wrong and the worst happens you may well be in a whole world of trouble you could find yourself in prison and thats before you even start to think about the costs. This is why public liability insurance cover is so high.

If you have bought a 6m rib that is only rated for a 90hp then something is seriously wrong somewhere....

nigel52 · 25 August 2013, 17:19

Thanks for all your replies. It is rated at 90hp max so will have to live with it.

whisper · 25 August 2013, 17:24

Unfortunately yes, or until the manufacturer is willing to change the CE plate on your rib if they gain a higher max hp rating for that craft and I would also get this in writing with your serial number documented

matt h · 25 August 2013, 17:28

Yep yep yep! Unusual for a 6 mtr only to take a 90. Most uk built ribs can go to 150 hp . Its rated for a reason. Could be the transom is not man enough for the extra beans Mr Taggart!

ShinyShoe · 25 August 2013, 17:47

Quote:

Originally Posted by nigel52

My reasoning was that the 115HP ETEC is still lighter than other 90HP outboards and it should not be too much of an issue.

Its not just the weight but the additional force that the engine will push with. If it didn't have any additional force you wouldn't be bothering...

whisper · 25 August 2013, 17:50

Quote:

Originally Posted by matt h

Yep yep yep! Unusual for a 6 mtr only to take a 90. Most uk built ribs can go to 150 hp . Its rated for a reason. Could be the transom is not man enough for the extra beans Mr Taggart!

Yep, it will be down to the design of the rib, I've never seen one but looking at this video the hull looks quite small for a 6m?

Piranha 6m RIB - YouTube

tonto · 25 August 2013, 18:25

I have a similar question really, and I supposed the answer will probably be the same!

My transom is rated for 200 HP, and 220Kgs, but what if I wanted to put on a 200HP etec, HO DHX, which is 228Kgs, I guess my insurance will probably say no? Are they that tight about 8Kgs? or put another way a measly 3.6%

Pikey Dave · 26 August 2013, 09:04

Quote:

Originally Posted by tonto

I have a similar question really, and I supposed the answer will probably be the same!

My transom is rated for 200 HP, and 220Kgs, but what if I wanted to put on a 200HP etec, HO DHX, which is 228Kgs, I guess my insurance will probably say no? Are they that tight about 8Kgs? or put another way a measly 3.6%

There's probably a law against it, if not we could always start a campaign to get one introduced:P

tonto · 26 August 2013, 09:14

Quote:

Originally Posted by Pikey Dave

There's probably a law against it, if not we could always start a campaign to get one introduced:P

Cant answer that one without breaking your rule 2 and 3

9D280 · 26 August 2013, 12:17

Sometimes you just gotta roll with it...... 3% isnlt a big number, but if it's bigger than your transom can take it might be the most expensive 3% you've ever overlooked.....

My hull is of a vintage where most 60-ish Hp engines of the time had 2 cyls, were premix and as a result were light. My transom will allow me 110Kg / 60Hp.

You would be surprised how many 2- stroke auto mixers (would have been new tech when my boat was built) are too heavy......

It's part of the reason I got the clamshell - 83Kg incl power trim, but a PITA to service, as every component holds 3 others in place so nothing is simple to change out!

Fish around- you may find there is a lighter 200 out there...... (and remember that a lot of 4- strokes quote dry weight)

whisper · 26 August 2013, 12:37

The Humber website shows the transom weight for each size but I don't really get why the 6.5 is not in keeping with the rest of the range.

Best give them a call and have a chat with them about it.

davej · 26 August 2013, 18:13

Do you really think they are a 'B' to service etc, as I really love my little 60 merc and considering its age think its the dogs b..Ks.

Yes, its a tad compact but that enables me to fit my little Yam Malta Aux alongside it without a bracket and it goes well on my tornado 5mtr.

I would like to put a yam 90 2S on but thinks thats a few yrs in the future, if any remain for sale.

Dave

9D280 · 28 August 2013, 09:22

Quote:

Originally Posted by davej

Do you really think they are a 'B' to service etc, as I really love my little 60 merc and considering its age think its the dogs b..Ks.

Plugs & fuel filters kind of thing they're fine, but if you need to take a carb out you have to dismantle the whole front end of the engine! - Most OBs the air box is simply that - Undo 4 screws, it falls off & carbs are in front of you. Clamshell? Air box holds up a ton of wiring, the choke solenoid, the cowl support.....

Thankfully don't need to do that very often.

Quote:

Originally Posted by davej

Yes, its a tad compact but that enables me to fit my little Yam Malta Aux alongside it without a bracket and it goes well on my tornado 5mtr.

Which is why I like them!

Pikey Dave · 28 August 2013, 14:56

My last boat, a RC 585 was rated to 150hp. I put a 175hp Ficht RAM on the back which was the same block as the 150/135, so the same weight. I told the insurance company this, they asked me what the max speed the combo was capable of; they went away & spoke to the underwriters & agreed to insure the boat, no problem.

Maximus · 28 August 2013, 17:32

Quote:

Originally Posted by Pikey Dave

My last boat, a RC 585 was rated to 150hp. I put a 175hp Ficht RAM on the back which was the same block as the 150/135, so the same weight. I told the insurance company this, they asked me what the max speed the combo was capable of; they went away & spoke to the underwriters & agreed to insure the boat, no problem.

Same Story with my Ribcraft 6.8 'Raptor'...225 Rated to 250 DF (Same Basic Engine).. See previous threads..and the Ribcraft 545 'Mr Jingles' for that matter.. 90 Merc four stroke to E-tec 130...
Most important thing...AS WELL as insurance OK!... is to get the right Boat!... i.e. strong enough Transum,Hull, ect to Power up!