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Greetings from Finland
Tapani:
And the last one
Hyperacme:
Looks like a long shaft motor and at level with keel should be good.
New Merc's in the 75 to 115 HP range are about 360 lbs. so not to heavy compared to older inline 6's and V4's which were about 300 to 350 lbs. range.
https://www.mercurymarine.com/en/us/engines/outboard/fourstroke/75-150hp/
I don't know ..
Sorry if this is dumb questions .. but ..
Have you pulled drain plug and tilted front of boat up as high as it will go .. make sure there's no water in hull under floor ?
Do you have a very large fuel tank and more then one battery in stern ?
Maybe motor is to high and not to low ?
How fast is max speed ?
Tapani:
Thanks for your reply.
I have an electric pump to empty the hull, not much water there.
Just one battery at the stern, two fuel tanks, 12 gallons in total. One empty last time we tried.
Top speed 33 knots @5700 rpm roughly.... only few seconds to planing. Trimming would raise the rpms.... too high I guess? Should I try another prop first? Maybe a High5? I don't mind loosing a bit speed.
As an absolute beginner: is the motor height setting different with this type of ahull from the norm? Manufacturers recommendatio is spot on with the Merc.
Tapani
Hyperacme:
33 Knots equals 38 MPH .. which seems pretty good if it's a GPS reading, old pitot tube speedo's can be off.
Your max RPM's as per Merc is 5800 RPM's.
What pitch / brand of prop are you using ?
Tapani:
Hello,
Yes, GPS reading.
First time I checked..... its 854360A45P16 Mercury, so it's a 13.25x16.
Hmmm...... A lot easier to swap the prop to a higher pitch than raise the engine.
Attached is lower boat weight part of the prop table from the factory manual.
For an 18 foot 1800 lbs boat (pay load included) I'd look at a 13.25x20 Laser II, a 12.75x20 Hi5 or a 13.75x19 Trophy.
Most of what we expect to do is two persons, 20-25 knot cruising. And naturally try to get rid of the porpoising and reduce nose lift during hole shot.
As it is now it porpoises almost dangerously (with even a touch of trim from the very low position), massive bow lift during hole shot, it's difficult to steer at speed, pulls to the right and when releasing the throttle it veers strongly to the left.
Any comments and ideas are greatly appreciated.
/Tapani
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