Trialing new F70 Yamahas on my 5.2m Kevlacat

[Lovey80]

Are your motors Xlong 25 inch? Also, I should ask about trailer axles. Mine are the factory Alko rubber torsion style, which I would like to replace. I have to decide whether to go with the same or convert to leaf spring.

I rang alco in brisbane last year to ask about doing the same. It worked out at $1350 from hub to hub per axle. Worth it just to be able to bolt off bolt on in my books

Edit: I believe mine are the originals since 1998 and I have no fear of them rusting through at this point but after 18 years I am worried that the rubbers may flog out soon so will replace them.

[Danf]

I rang alco in brisbane last year to ask about doing the same. It worked out at $1350 from hub to hub per axle. Worth it just to be able to bolt off bolt on in my books

Edit: I believe mine are the originals since 1998 and I have no fear of them rusting through at this point but after 18 years I am worried that the rubbers may flog out soon so will replace them.

They get completely submerged during a launch, they fill with salt water and you can not judge how much corrosion is going on inside.
At least with springs, you get a better idea and you can wash them easier.
But, at the end of the day, it is an easier retrofit.

[Lovey80]

They get completely submerged during a launch, they fill with salt water and you can not judge how much corrosion is going on inside.
At least with springs, you get a better idea and you can wash them easier.
But, at the end of the day, it is an easier retrofit.

I had that fear also a couple of years back. When I rang Alko they said that they have never had an axle back in rusted out before the rubber eventually went. Considering these are going on 18 years now and haven't rusted out (though by the look of them you would think they are ready) I wouldn't worry about the corrosion. I am thinking though that when I replace them I may put a hose fitting in the top to be able to quickly flush them out from the inside easier.

[Mupster]

Interesting thread. How much does a typical 5.2KC hull weigh? I ask because I have a 5.2 Devilcat that weighs about 1100 kgs that I have to repower and was thinking that 70hp 4s would be too small for it but reading the tread maybe it's an option.
Originally most 5.2 Devils were powered by Yammie 90hp 2s and I was thinking 90hp 4s Sea Pro Mercs or 115hp 4s Counter rotating Sea Pro's but was concerned with the weight. Any thoughts? 70hp's are cheaper than 90/115hp.

[Flex]

Heres a few pics of mine,
happened 800km from home.. wasn't pretty
Had to use a ratchet strap around both front arms to stop the wheels faling out all together.
When it was removed the front right fell off onto the road at Rocky..lol
Alko axle.jpg
alko axle2.jpg
alxo axle 3.jpg

[Noelm]

Good looking boat (not so good looking axle) just thinking about selling my centre console cat and looking for a late model Sharkcat like that, either with pods or without

[Danf]

Heres a few pics of mine,
happened 800km from home.. wasn't pretty
Had to use a ratchet strap around both front arms to stop the wheels faling out all together.
When it was removed the front right fell off onto the road at Rocky..lol
Alko axle.jpg
alko axle2.jpg
alxo axle 3.jpg

That's what worries me about not being able to see inside the axle tube where the rubbers are.

[Danf]

Interesting thread. How much does a typical 5.2KC hull weigh? I ask because I have a 5.2 Devilcat that weighs about 1100 kgs that I have to repower and was thinking that 70hp 4s would be too small for it but reading the tread maybe it's an option.
Originally most 5.2 Devils were powered by Yammie 90hp 2s and I was thinking 90hp 4s Sea Pro Mercs or 115hp 4s Counter rotating Sea Pro's but was concerned with the weight. Any thoughts? 70hp's are cheaper than 90/115hp.

I can not remember the weight of the Kevlacat, but I am pretty sure it is under 1000 kg.

[Flex]

Good looking boat (not so good looking axle) just thinking about selling my centre console cat and looking for a late model Sharkcat like that, either with pods or without

Thanks Noelm,
Had the boat out a few times now. Goes fantastic I must say. I'm lead to believe the non-podded version rides a smidge better? Ive never been in one so cant comment.
But the extra deck space is fantastic and well worth it, if a little wet atm with 115's

[Lovey80]

Flex was that a result of the rubbers flogging out or did it rust through?

[Flex]

Flex was that a result of the rubbers flogging out or did it rust through?

Rubbers were fine.
If you look at the top pic closely you will see the arm that gets pressed into the axle/rubber has a sort of stub axle attached to it. maybe 300mm long or so.
This is what was rusted away totally and caused the wheels to fall off..lol.
Also the inside of the actualy axle itself was fairly rusted.

before I drove away it didn't look to bad from the outside.

[Lovey80]

How old was the trailer when that happened?

[No Excuses]

No doubt the 70 yammy is different to the 60 however I believe there is no replacement for displacement. At 1 litre (60 yammy is the same) the 70 yammy is half a litre behind the zuke. I see the rev limiter is 6300 rpm on the 70 yammy vs 6000 rpm on the 60 yammy. My concern is the extra 10hp is being achieved in the last 300 rpm which no one will ever use but technically it's legit on paper as far as Yamaha is concerned. Anyway that's my 2 cents of uneducated opinion haha.

[The Mad Cat]

From memory the salesman who just sold us an F70 said the F60 produces 60 hp at 5600 and the F70 hp is at 5800. I think I read that somewhere also.

TMC

[Danf]

The other issue that I have to consider is the fact that I can re power with Mercury 60 Hp 4 strokes which are available from the only local outboard place in town. Interesting to get figures on this boat / motor setup.