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Message board > Navigation & sea worthiness > navigator 18 top speed

Message 7 of 7
Posted by member George MacDonald on Sunday 23 January 2022

Hi guys, a friend of mine has put up this video he took while out on my navigator one night, nice calm evening. 33knots at 5400 rpm.


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Message 6 of 7
Posted by member Gary Steele on Tuesday 24 August 2021

I always thought 50hp was the recommended maximum. Either way a stern heavy Navigator at 32kts sounds scary !

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Message 5 of 7
Posted by member Simon Papendick on Sunday 22 August 2021

Hi George
The weight would be the weight of a 70 hp two Stoke and not the weight of your 90 hp four Stoke which is about double the weight that the boat was designed to take when it was first build and designed to take.
Simon Papendick

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Message 4 of 7
Posted by member George MacDonald on Sunday 22 August 2021

Thanks guys, will check revs later today and let you know. 32knots is pretty fast for a boat like this but I still would've expected an increase in speed with more pitch. Simon do you by any chance know what the maximum engine weight was supposed to be for these hulls so I know how far over I am? the boat doesn't seem to be sitting too low at the stern.

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Message 3 of 7
Posted by member Keith Lathwell on Sunday 22 August 2021

If you are not hitting max revs with the 19" pitch prop you have gone too high with the pitch. I would suggest that 32knots is plenty.
Rgds Keith

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Message 2 of 7
Posted by member Simon Papendick on Sunday 22 August 2021

Hi George,
As a former employee of Hardy Marine during the 1980's. The Navigator 18 was not originally designed to have an engine the size of your 90 hp. The boat design was to have a maximum of 70 hp two stoke, not a 90 hp four stoke/
Firstly the added weight will keep the transom way lower than it should be and it will put excessive stress on the transom layup and could cause failure to the hull if it is used over a prolonged period of time. The increase of pitch on the propeller will get you on the plane quicker, however, it will reduce the upper rev range, this why you are not seeing any increase in speed. the rev range it reduced so you are likely to have maxed out the engine.


Simon Papendick
J-Star Marine Services
Former Hardy Marine employee 1983 to 1990

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Message 1 of 7
Posted by member George MacDonald on Sunday 22 August 2021

Hi guys
Just wondering if anyone knows if the navigator has a "maximum hull speed"?
I've got a mariner 90 4 stroke on the back coupled with a set of nauticus smart tabs and last season I was running 32knots full speed with a little engine trim and a 17pitch prop. I've changed the prop to a 19 now and still only seem to be getting 32 with the same engine trim. surely the prop would have given me at least a couple of extra knots?
any thoughts would be much appreciated.

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