5.4SR engine offset

no excuses · 15 January 2009, 07:17

how far should I offset my motor, my center consul and seat are offset all the way to the right (starboard) side. My fuel tank (12 gallon) will be under seat and battery under consul. I have read on here that it should be offset about 1.5" to the right to componsate for tourqe. Thanks stan

Jono Garton · 15 January 2009, 09:38

Hi

With a 35hp it wont make much difference, if the holes are drilled it would be a mistake do re drill close by. They will go from o to 0

Jono

doggypaddle · 15 January 2009, 09:39

Depends on the size of the engine, bigger engine = more offset.
1.5" is fine for most engines commonly fitted. 75-90HP range,
smaller engines theoretically need less offset but its not critical, if the transom is already drilled i would use the existing holes.
What size is the engine? not the 35hp you have on your details i hope? that wont be very exciting

you will need a fine pitch prop on that to get anywhere at anything other than displacement speeds with any weight on board, it may take a while to get out of the hole if you have the flooding hull

no excuses · 15 January 2009, 10:54

upgrading to a 90hp yami so it should perform a lil better. Although the lil 35hp merc would go right at 25mph with two on board without dive gear. Start adding gear and it would start dragging it down pretty quick.

doggypaddle · 15 January 2009, 11:55

Quote:

Originally Posted by no excuses

upgrading to a 90hp yami so it should perform a lil better. Although the lil 35hp merc would go right at 25mph with two on board without dive gear. Start adding gear and it would start dragging it down pretty quick.

You should get 36-38 knots with a good 90 yam on a 19"prop.
my 80 yam has a 17" prop and i get 34kts with 15 stone and 100l of fuel aboard.
Nos has a 19" and a yam 90 and gets 38kts with 100L of fuel and him aboard. i guess 40 knots would be achievable with less fuel and a racing snake at the helm

Nos4r2 · 15 January 2009, 12:48

Quote:

Originally Posted by doggypaddle

Nos has a 19" and a yam 90 and gets 38kts with 100L of fuel and him aboard. i guess 40 knots would be achievable with less fuel and a racing snake at the helm

I do wonder if that's actually true. I noticed that with 2 aboard my WOT revs don't change-slip increases a bit and I lose a bit of top speed.
That might be down to my specific prop though. ( I suppose it might slip less at WOT with even less weight...)

no excuses · 15 January 2009, 14:49

The old motor mounting holes are filled up. So with 2-4 divers and gear on board plus 70l of fuel and other gear, what prop would you go with, a 15",17" or 19" prop. Stock Yamaha aluminum. Thanks again.

Nos4r2 · 15 January 2009, 15:19

Quote:

Originally Posted by no excuses

The old motor mounting holes are filled up. So with 2-4 divers and gear on board plus 70l of fuel and other gear, what prop would you go with, a 15",17" or 19" prop. Stock Yamaha aluminum. Thanks again.

Assuming it's a 90 2 stroke, start at a 17"-but watch the revs if you're solo.

doggypaddle · 15 January 2009, 16:22

Quote:

Originally Posted by Nos4r2

Assuming it's a 90 2 stroke, start at a 17"-but watch the revs if you're solo.

I will second that, 17"or19" a 15 will be too fine i would think especially if you use the boat solo. I would think a 19" may be just about OK depending on how heavy all the gear is and how often you use it with that load. assuming its a K series yam prop.

PeterR · 15 January 2009, 17:08

Quote:

Originally Posted by no excuses

how far should I offset my motor, my center consul and seat are offset all the way to the right (starboard) side. My fuel tank (12 gallon) will be under seat and battery under consul. I have read on here that it should be offset about 1.5" to the right to componsate for tourqe. Thanks stan

I was told once the searider is an exception to the slight offset of an outboard as the reason for the console being offset is to counter act the engine torque and not as many poeple beleive to carry a stretcher(it came from the military but i cannot prove if its right or not maybe someone can ask avon

matt h · 15 January 2009, 18:03

i got told it was for carrying capabilities too from Tony Steadman at Avon

PeterR · 15 January 2009, 18:59

Quote:

Originally Posted by matt h

i got told it was for carrying capabilities too from Tony Steadman at Avon

Hi Matt,Are you still suffering from paint fumes

What are capabilities?

matt h · 15 January 2009, 19:03

i have no idea!! reckon them talking sh-te!!!

no excuses · 15 January 2009, 20:39

well on my way to pick it up, looks like I will offset it 1.5" to starboard and start out with a 17" prop.

matt h · 15 January 2009, 20:41

you wont go wrong with that, of course we want pictures!!!

no excuses · 24 January 2009, 03:55

Quote:

Originally Posted by matt h

you wont go wrong with that, of course we want pictures!!!

Will get pics up in a few days. Motor was completly rebuilt so have to break it in, have gotten a few hours on it, just enuff to crack wide open the throttle and have some fun for short bursts. Have a few issues, the trim on the controller will not trim down, just up but it works on the motor. Had another controller on it and it worked, but it was a pull to open controller. Analog tach is reading at about double rpm. But with it tucked all the way under I am getting 42mph with myself, 68l fuel, and about 300lbs of dive gear plus assorted other gear. Have to say that I am very happy with it. I could prob get a few more mph out of it when I can trim it out and not packing near as much dive gear, but its sure is fun as is.. stan