New motor height dilemma!

[stevet]

Hello members

I have posted the following on a couple of US forums and I am seeking local input.

I have repowered with a G2 115 HO from a Mercury 125hp 2 + 2 stroke on my Allison Fisherman 175 which was manufactured with a pod.

Before playing with props I would like to get the height right. The motor is currently fitted with a RX3 15” with it achieving around 6050 rpm


The G2 is mounted as high as it will go. The selling dealer says it’s not a problem as there is no rooster tail. Not sure about this, however I see this as a boat problem and not a motor installation problem.


Unfortunately at WOT the anti cavitation plate is buried. See video link

https://youtu.be/ghNTIcWDpgw


I think I need about 2” – 50mm of further height.

I am hoping not to put a fully adjustable jackplate on that further extends the motor behind the motor and are hoping for an option that adds around 1” 25mm to the setback

Do folks know of options?


cheers
stevet

[Dignity]

Hello members

I have posted the following on a couple of US forums and I am seeking local input.

I have repowered with a G2 115 HO from a Mercury 125hp 2 + 2 stroke on my Allison Fisherman 175 which was manufactured with a pod.

Before playing with props I would like to get the height right. The motor is currently fitted with a RX3 15” with it achieving around 6050 rpm


The G2 is mounted as high as it will go. The selling dealer says it’s not a problem as there is no rooster tail. Not sure about this, however I see this as a boat problem and not a motor installation problem.


Unfortunately at WOT the anti cavitation plate is buried. See video link

https://youtu.be/ghNTIcWDpgw


I think I need about 2” – 50mm of further height.

I am hoping not to put a fully adjustable jackplate on that further extends the motor behind the motor and are hoping for an option that adds around 1” 25mm to the setback

Do folks know of options?


cheers
stevet

Steve,it is running too deep but it also looks like you didn't trim the motor out once underway, that will help. I ended up replacing my pod which changed the dynamics but I guess you don't want to go down that path. Basically for every 300mm past the transom you need to raise your cav plate 25mm. Your pod looks a little different to what I've seen in that the top has a lip, is it 1600 mm long. My mate with a 195 (same as mine) is going through the same process. He is going to get an alum plate probably 20mm or 25mm thick, ive forgotten the grade but bolt that on with countersunk bolts and rebolt the motor higher. If you go down that path make sure you can go either up or down at least one more hole.

Did they put an extra long shaft on by any chance, plenty of people out there still trying to line up the bottom of the hull with the cav plate.

[stevet]

Hi Dignity

the boat was supposed to be built for 25" shaft but stranger thangs have happened

I would love to see the plate arrangement - re the changing of the pod my pod is moulded with the hull - i think yours was a bolt on type?

thanks

Steve

[Dignity]

When it happens I'll send you some photos. I reckon a 20 " would have sufficed although it would have the motor sitting in the wash more. Yours does suffer some when it comes off the plane, raising it would be healthier for your motor.

[stevet]

I am thinking of these - recommended as being stronger than others

https://bobsmachine.com/product/vert...sion-brackets/

[Chimo]

Basically what Dignity said but also do need to see what happens when you trim the motor back.

Is the motor the 3 cylinder unit? I was considering getting two of the new 3 cylinder 115 HP to replace my existing 115s

Cheers
Chimo

[Noelm]

The dealer is saying it's not a problem because there's no more height available without add ons, as it is, it's probably "acceptable" but, when it's new, you want perfect, only trial and error will tell for sure.

[Dignity]

Steve, I would be suggesting you find somebody other than the dealer when you get your motor serviced. He is a w....r, I understand that he can not do anymore without add ons, but he should have alternatives he can suggest, I guess it all depends on your agreement at purchase time.
Those plates will work and is probably the quickest option.

[stevet]

Is the motor the 3 cylinder unit? I was considering getting two of the new 3 cylinder 115 HP to replace my existing 115s

It is one of the I3's certainly strong, quiet and refined, the fly by wire takes some getting used to as it takes so little effort to operate the boat . The power steering is effortless - punches out of the hole onto the plane it will be interesting to compare when set up is sorted

If you were Sydney or environs would be happy to meet up.

[stevet]

Steve, I would be suggesting you find somebody other than the dealer when you get your motor serviced. He is a w....r, I understand that he can not do anymore without add ons, but he should have alternatives he can suggest, I guess it all depends on your agreement at purchase time.
Those plates will work and is probably the quickest option.

the bitch about the plates is the US shipping doubles the price - I would have been happy to pay the dealer for the extras - unfortunately his deal is not to do water test and re a 20" might have been sufficient - the dealer previously sold Allison's

[Chimo]

stevet

The guy who services my motors makes jack plates so he may be a local option for you.

[stevet]

stevet

The guy who services my motors makes jack plates so he may be a local option for you.

would you be able to post the contact details?

stevet

[Out-Station]

Stevet, just another thought, how much "out" trim are you getting on the plane with regular operating load on board before you start get some prop aeration. If you getting nearly the whole range/gauge then imo you could say its well to deep and you will get good results working on it more. If your only getting half the gauge before you get some aeration but still enough trim to work with then maybe its not as big as problem as what it may look to be. Maybe another thing to test before you start spending $$$.
Scott

[Chimo]

Have you got pictures with the motor trimmed back and up? Or have you looked at the motor when it is trimmed up?

[stevet]

I will go through what I have to se what I can find