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 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 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.

Regards

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

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