Engine too low in water?

[The Gurnard]

Originally Posted by jeffstevens763@g

Just out of intrest my transoms 15 inhes leg 17 1/2 inces plate 1/2 inch below keel.

Jeff..I can give you first hand experience of my Quicksilver 4.3 HD . Its transom is/was 16” dead. The OB is the Mariner 25HP two stroke..length 17.5 inches shaft.

I did not use a packing piece..it threw up no spray ..and went plenty fast.

You followed that boat many times so will know how it performed.

Initially … I put a ½ inch packing piece in to lift the boat..I swear it did not make any noticeable different to my top speed when using gps ..nor the wake coming out the back..so I didn’t bother lifting it. It did appear to ventilate a bit more ..but that could have been due to trim .. sea conditions ..slightly soft keel ..or imagination


I drilled the bolt holes and it was fixed thereafter. Any time you saw the boat ..it was running with AV plate 1.5 inches. below transom

[Richd]

The Gurnard, that's a good article you linked to earlier, thanks. I'm running as light a set up as possible with just 5hp so makes sense to optimise this. Transom is almost 16" so hopefully there's some room to raise a bit on the mounting plate.

[jeffstevens763@g]

Originally Posted by The Gurnard

Jeff..I can give you first hand experience of my Quicksilver 4.3 HD . Its transom is/was 16” dead. The OB is the Mariner 25HP two stroke..length 17.5 inches shaft.

I did not use a packing piece..it threw up no spray ..and went plenty fast.

You followed that boat many times so will know how it performed.

Initially … I put a ½ inch packing piece in to lift the boat..I swear it did not make any noticeable different to my top speed when using gps ..nor the wake coming out the back..so I didn’t bother lifting it. It did appear to ventilate a bit more ..but that could have been due to trim .. sea conditions ..slightly soft keel ..or imagination


I drilled the bolt holes and it was fixed thereafter. Any time you saw the boat ..it was running with AV plate 1.5 inches. below transom

my mercury was supplied with packers i never used anything on that boat with this engine cav plate was level with the keel

[jwalker]

It depends whether you have a hard hull or a flexi hull. If you're running a sib the floor will be flexed upwards, consequently the water movement at the stern is downward from the flexed floor to the transom. Even if the sib has a central hull support member the hull is still only near level at the hull centre. The hull is a hooked hull so running with a set up similar to a solid straight hull won't be the same. Carry on....