Difference between Max Recommended Power and Max Power Allowed?

BuffsBoat · 07 January 2013, 12:53

Hi group...

What is the difference between the Max Recommended Power and Max Power Allowed as defined by the manufacturer? Particularly when it comes to insurance?

My boats max recommended power is 25 HP, but the max power allowed is 35 HP. What would happen if I opted with a 35? Would it put more stress on the transom? Make the boat harder to control?

Thanks for the continued advice!

9D280 · 07 January 2013, 13:49

As a general rule in simple terms:

Reccommended = "more & it becomes a handful to drive"
Allowed = "more & you break it"

Insuance wise it's likely the Max, although if you do a search on here there seem to be quite a few companies don't seem to care when you ask for a quote - but I'm sure would suddenly care if you hurt someone / broke someone else's boat. I'd wait for the US crew to fill in the details as I'm sure your insurance will work differently to over here.

As for stress on the transom, yes, more HP is going to give it more abuse to withstand, and as a general rule, more HP = More weight. You may find around that HP that the extra weight of a 30 that's a de- tuned 40 will make the handling worse, so you're actually better with a 25 that you can open the throttle on. Could you borrow an engine to test with?

Also bigger engine on a tiller = sore arms after a while.

SPR · 07 January 2013, 15:04

recommended = normal person , normal use

Max rated = Ribnetter or Dive Boat, heavy loaded

S.

captnjack · 07 January 2013, 15:30

I doubt 25 vs 35hp would make one whit of difference to your insurance here in the States. My companies have mostly wanted to know my max speed and my operator experience/training. This is because their costs if you break your transom or not are really irrelevant to categorizing your risk and setting your premium. The bulk of the insurance liability comes from morons running over children and such things.

If you are just taking your family out fishing and zooming around a 25hp is plenty on a MkII. If you have a really heavy load of diving gear then consider the 35hp. I "only" had 25hp on my Bombard C3 which is similar to your boat and it was fast enough and handled an ample load.

jyasaki · 08 January 2013, 18:05

I suspect it will come down to the insurance carrier. Some will ask about ratings, some don't. I have heard of people having claims denied when it was discovered they were overpowered (mostly on hard boats; there's more of them over here), but I have no idea how common it is.

jky

lightning · 15 January 2013, 08:04

I have a Zodiac 2.85m SIB and it is rated to 6hp with a max of 8hp. The boat has a solid floor with an air keel.
I am using a Tohatsu 9.8 hp two stroke on it, and this gives a maximum speed of just over 20mph. (against about 15mph with my old engine which was a 6hp 4-stroke)
The boat seems to handle the "power" of the 9.8hp motor without any problem, obviously the weight is not an issue as the Tohatsu only weighs 26kg, and the transom is rated to 38kg.
But is this setup going to get me into trouble if l have an accident? I mean is it breaking any law in the UK to use it? The boat is insured and l did give them updated details when l bought the new engine.

lightning · 20 January 2013, 16:01

Does anybody know the answer to this?

ppenman · 20 January 2013, 17:03

Quote:

Originally Posted by lightning

Does anybody know the answer to this?

A couple of years ago I wanted to change the engine of my Ribcraft 585 to a 175 hp even though the max power was stipulated as 150hp. When I spoke to my insurance company about this they said they would be happy to insure me providing I could get documentation from Ribcraft saying it would be ok. If not & I had a claim I was told I would not be insured. I bought a 150 instead.

Do you really want the risk of a 3rd party claim against you for personal injury.

Maximus · 20 January 2013, 19:03

Getting The Right RIB... that will even take the Max Power the Manufacturer's themselves recomend....Without..Chine Walking,or even Transums spliting, ect IS a Good Starting point!

lightning · 20 January 2013, 21:03

I will speak to the insurance company and may also try to contact Zodiac to see what they think, although I doubt I will get a reply from them.

Locozodiac · 21 January 2013, 14:59

280-290 sibs are rated for 10 HP, a light weight 9.8 being 170 cc will be ok, just inflate well all air chambers and keel to factory working psi and you'll be fine. Check your inssurance Company if they have an issue with it.

Happy Boating

lightning · 01 February 2013, 16:38

Thanks, it seems fine on the boat, as you say.

It will plane without hesitation with two adults on board, and performs really well. I only recently realised I was under-inflating the tubes, my Rule pump was only inflating it to about 1.5psi.
I bought a Bravo SuperTurbo low/high pressure pump and now it is much better.

Northern Pike · 04 February 2013, 20:33

Buffsboat, I had the exact same boat as you for several years. I started with a 9.9 but soon got rid of it. Way too small. Then I got a 2 stroke Evinrude 20 HP. It was a great motor. After a few years I modified it and made it into a 25. I got a little more speed out of it and was quite happy. It would move along at a good speed (20-23 mph IIRC) with 2 fully equipped cold water divers and a tender.
Going to 35 HP would likely mean another cylinder and associated weight increase which would largely negate any benefits. You might gain 2 or 3 mph and you'd burn more fuel. I think 25 is optimal for your boat.
This doesn't actually answer your question but hopefully it will be of some help. :^)

BuffsBoat · 05 February 2013, 18:44

Quote:

Originally Posted by Northern Pike

Buffsboat, I had the exact same boat as you for several years. I started with a 9.9 but soon got rid of it. Way too small. Then I got a 2 stroke Evinrude 20 HP. It was a great motor. After a few years I modified it and made it into a 25. I got a little more speed out of it and was quite happy. It would move along at a good speed (20-23 mph IIRC) with 2 fully equipped cold water divers and a tender.
Going to 35 HP would likely mean another cylinder and associated weight increase which would largely negate any benefits. You might gain 2 or 3 mph and you'd burn more fuel. I think 25 is optimal for your boat.
This doesn't actually answer your question but hopefully it will be of some help. :^)

thanks for this. this is good information!