Equates to about 200rpm, so you need a blade off a food mixer to give you 6200rpm?:g: Have you sorted your plotter/compass problem out yet?
blueskip

 

Equates to about 200rpm, so you need a blade off a food mixer to give you 6200rpm?:g: Have you sorted your plotter/compass problem out yet?
blueskip

pmsl.............skippy you are a very very cheeky boy...............:hammer:

 

pmsl.............skippy you are a very very cheeky boy...............:hammer:

To get 6200rpm he is going to have to go down significantly in prop diameter & pitch, your cant argue with fluid dynamics:nono: it will be interesting to see what the fitter says about it, but I reckon he will have to prop down a fair bit to get to 6200rpm from 4500rpm
blueskip

 

It does look like your prop is way out - would it be worth contacting Raider? - I know the boats are slightly different now, but your engine can't be an unusual choice and they might be able to advise you of a better prop to start from as a 'base' - I would also consider a stainless prop - I found it made a big difference on my boat.

 

barry i think that you have a nice surprise comming once they have your motor set up right! she will jump out of the hole and you will get a better top end. you really need to have the boat set up with your normal running load eg 2-3 people and tackle. fuel ect to get it dead right.
we had 3 props fitted until it was correct. and what a differance each one made.

baz.

 

Thats what i was thinking Vic, 1700 rpm is a lot to gain back. Will lifting the engine make any differance to the rpm. Headlight was down there trying out his engine. He has just droped from a 19 to a 17 on his honda 115, and is still only getting 5100 rpm.
Im hopeing Dave at west point will sort this out, iv been told hes a realy good fitter. The more i think about it, the more confused im getting. And with the listing, im realy confused.

PS Vic i plotted a course in the bay today, with the plotter. It was bang on, so one thing is sorted.

 

To get 6200rpm he is going to have to go down significantly in prop diameter & pitch, your cant argue with fluid dynamics:nono: it will be interesting to see what the fitter says about it, but I reckon he will have to prop down a fair bit to get to 6200rpm from 4500rpm
blueskip

Been there done that (well..............not looking for 1700 revs right enough though)..............a bit of jiggery pokery needed for sure..............it was the food mixer blade part which made me chuckle...............:notworthy

 

Thats what i was thinking Vic, 1700 rpm is a lot to gain back. Will lifting the engine make any differance to the rpm. Headlight was down there trying out his engine. He has just droped from a 19 to a 17 on his honda 115, and is still only getting 5100 rpm.
Im hopeing Dave at west point will sort this out, iv been told hes a realy good fitter. The more i think about it, the more confused im getting. And with the listing, im realy confused.

PS Vic i plotted a course in the bay today, with the plotter. It was bang on, so one thing is sorted.

Being new, the dealer will be bending over backwards to sort you out, by "lifting" do you mean by physically lifting it up? or do you mean trimming it out? trimming it out might make a difference to the rpm, but not necessarily improve the situation, all it will do if you trim out too far is cavitate like hell. Dont worry about it, as Backlash said he had to have his repropped 3 times to get it right, by the time the supplier has finished, it will be like a magic carpet!
blueskip

 

Being new, the dealer will be bending over backwards to sort you out, by "lifting" do you mean by physically lifting it up? or do you mean trimming it out? trimming it out might make a difference to the rpm, but not necessarily improve the situation, all it will do if you trim out too far is cavitate like hell. Dont worry about it, as Backlash said he had to have his repropped 3 times to get it right, by the time the supplier has finished, it will be like a magic carpet!
blueskip

He means physically lifting it up the transom. He reckons it can only be that and the prop size.

 

if the leg is to deep in the water it do cause a drag. (how the hell this makes a differance with 115 gee gees pushing it gods knows ) the yanks have power lifters that raise the engines as well as the trim and tilt.
they lifted ours one hole as well, all good as long as its not over done as it will slip on tight turns.

baz

 

if the leg is to deep in the water it do cause a drag. (how the hell this makes a differance with 115 gee gees pushing it gods knows ) the yanks have power lifters that raise the engines as well as the trim and tilt.
they lifted ours one hole as well, all good as long as its not over done as it will slip on tight turns.

baz

backlash, i think he was refering to the engine sitting to deep. And that was causing the listing due to the torque from the prop, but he did say it can help with the rpm aswell. But it will need to drop on the pitch of prop. But god nows how far it will have to be droped. Lifting the engine worked for you did it.

Clinker, you have a point there, think i will give Raider a ring. I know they dont aknowledge the uK built raiders. But must have fitted 115's to them, so it should give us a starting point.

 

barry lifting the engine higher by one hole approx 2inches did make a differance. but i think that your prop must be way out to be that far down on revs.

baz

 

hi mate,
i had a 115 four stroke on my raider had a few problems like your self
if u lift the engine up the raider will start to cavatate. i would try your prop first. i went through all the usaul things could not get it to rev obove 4,8oo in the end it was down to crushed fuel line and the wrong size main fuel line. sent it back to merc i would give raider a phone see what they say.

 

Outcast you have a PM.

 

Thats what i was thinking Vic, 1700 rpm is a lot to gain back. Will lifting the engine make any differance to the rpm. Headlight was down there trying out his engine. He has just droped from a 19 to a 17 on his honda 115, and is still only getting 5100 rpm.
Im hopeing Dave at west point will sort this out, iv been told hes a realy good fitter. The more i think about it, the more confused im getting. And with the listing, im realy confused.

PS Vic i plotted a course in the bay today, with the plotter. It was bang on, so one thing is sorted.

if the engine is too low the drag on the leg is phenomenal instead of it being in the sheltered water behiind the stern it is exposed and i think you will find a huge difference when raised think you could be looking close to 40kts with the right prop

 

Barry

When correctly propped and fitted you should get about 40 knots WOT.
The engine will hopefuly have been fitted a fraction of an inch off centre (to starboard). If not, this can cause some of the list through prop torque.
If fitted centre, you can make an adjustment to the little rudder under the cavitation plate.

Lifting the whole engine a fraction will create a lot less drag which "may" improve RPM a little, but will also mean that whilst she goes faster, she is likely to cavitate in turns.

Getting the correct pitch and diameter prop is going to be the key to getting the engine revs right.

As an example, the correct prop on a Suzuki would be a 14x19. This may not translate over to a Mercury.

 

Barry

When correctly propped and fitted you should get about 40 knots WOT.
The engine will hopefuly have been fitted a fraction of an inch off centre (to starboard). If not, this can cause some of the list through prop torque.
If fitted centre, you can make an adjustment to the little rudder under the cavitation plate.

Lifting the whole engine a fraction will create a lot less drag which "may" improve RPM a little, but will also mean that whilst she goes faster, she is likely to cavitate in turns.

Getting the correct pitch and diameter prop is going to be the key to getting the engine revs right.

As an example, the correct prop on a Suzuki would be a 14x19. This may not translate over to a Mercury.

The engine has been offset, he told me that today on the phone.

 

barry you have a pm

 

The engine has been offset, he told me that today on the phone.

Try adjusting the rudder a little...
Worst case is it needs offsetting further to counter the list.

Or some redistribution of weight which isn't great as when the boat does come out of the water on the plane, she'll flop to the other side.

 

Try adjusting the rudder a little...
Worst case is it needs offsetting further to counter the list.

Or some redistribution of weight which isn't great as when the boat does come out of the water on the plane, she'll flop to the other side.

I wont be touching it Tom. Im leaving it to the fitter who fitted the engine. I just wanted to get some info for myself, i trust the fitter who is an established Merc dealer. Who has a good reputation, so i will see what he has to say once he has taken it out. He said that the 90 that was on it was offset, and he was happy with that so it was a case of just bolting the new engine on. But it looks like he has to make a few adjustment, and select the right prop for me. He has a 17 prop he is going to try first, to see what change that will give.

 

It will be great to hear the results.
As well as you getting it running perfect, it will help others get it right to.

 

Something else i forgot to mention aswell, is that when traveling at speed the boat feels like it wants to turn right. So i have to constantly have to place preasure on the wheel, to combat the boat turning. Iv never had this problem on any boats in the past, but then iv never had an engine of this size before.

 

Come to think of it, correct me if im wrong. If the engine is offset, to starboard. And is sitting to deep, which is creating drag this will force the boat into a right turn.
I thought this may be the case, as when i had my kayak. If rowed and then pushed the oar in to the water at the side of the yak, it would turn in that direction. Im probably wrong tho. lol

 

I've been on the red for much of the eveing so trying to work it out, but if offset to starboard, when the engine is in gear it will force you to port.
If out of gear then it will create drag and turn you to starboard.

It sounds like it "may" need more of an offset? Bear in mind I am not an outboard engineer, just trying to work out what would make sense.

 

Had exactly the same problem ( boat trying to turn to the right underway ) and it was quite a strong pull to the right.

The solution was to adjust the trim anode as Tom suggests by moving the trailing edge of the anode towards the direction of the pull.

( i.e If pulling to the right then move the anode to the right ).

On my E-Tec it is actually not possible to move the anode the other way ( i.e can only move it to the right ) and a small movement makes a BIG difference.