Engine compatibility

[Dan Gurney]

Just a 'what if...?' this.

I was looking at the hull ID plate on my RIB (ex-Woody73 Humber Attaque 5.35) the other day for insurance purposes. The plate says it's rated for a max hp of 150. Given the fact that it's an early nineties boat (as far as I'm aware) does this mean that this rating is based on the assumption that we're talking about a 2-stroke. If so would a four stoke that weighted the same as an early nineties 2-stroke be ok as a replacement if it ever came to it? Something in the 90-115 sort of bracket?

Like I say, this is just a 'what if...'; I'm hoping the 85AET doesn't explode first time I put it in the water!

[Mextli]

your insurance will insure your boat if it has the correct engine, and that's determined by the maximum weight and the maximum HP allowed
If it allows you 110 KG and 50 HP like with my SR, i can put a 110kg weighting 50 HP motor on it, and the insurance will be fine.

[Dan Gurney]

No mention of an approved weight, only HP. There is a rating for the total load the boat can carry but and I guess the engine would be part of that weight but that doesn't tell you what weight the transom is designed to carry.

[jyasaki]

Sounds pretty normal. My boat (circa 2005) does not list a max engine weight either. Max load and max hp. Everything else is math.

jky

[9D280]

I had a similar problem with mine - But I was also aware that the transom seemed thin compared to 1990s boats I'd seen. (Mine's an '84 build) Turns out mine was rated for the old 2 cyl non autolube 60HPs. - 110Kg. There are even some 2- stroke 60s out there would have bee ntoo heavy! (part of the reason I am now running the Clamshell)

Get the serial number & give Humber a call - Sue(?) was helpful and got me the info within about half an hour of my call. With a 90's boat it might be while you wait!

[Downhilldai]

Back in the day, before 4-strokes came onto the scene, the manufacturers would give a hp rating and that would cover the weight of all motors available up to that hp rating. As time went on and engine development overtook RIB development, heavier 4-stroke motors (& some 2-strokes, eg 75hp Opti) arrived on the scene and people were fitting these to existing RIBs, keeping within the hp limit, but finding these were causing too much stern weight. Some manufacturers then implemented a weight limit to their boats, which in many cases, accorded with the heaviest 2-stroke motor available at the time the boat was developed. Some still don't state a max engine weight, particularly if the boat is beamy/buoyant at the stern and the heavier motors don't have such a bearing on overall balance.

[Dan Gurney]

Humber were very helpful. Engines up to 170kg. They reckon this means a 90.

[9D280]

Or twin ClamShell 60s...

Well worth checking detail.



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