Repower with modern 4 stroke?

[dizzyspots]

88 Mariner MR220V...capacity plate show max hp as 240hp. No motor weight listed...how would that translate to a modern 4 stroke...say 225hp?

 

[ahicks]

My advice would be to look at the different weights for each HP, and focus on the largest HP motors for each weight category.

Not Familiar with the motors in the size you might be looking at, but an example of what I'm talking about might be the Merc and Yammi 75-115 4 stroke engines are all about the same weight. To my way of thinking, there's little reason to buy a 75 when you could have a 115 for just a few more bucks, without the weight penalty normally associated with more HP.

 

[dingbat]

The 240 hp figure is based solely on a calculation based on hull geometry.

The weight of the outboard counts against the boats max. load capacity.

The closest you can get to 240 hp is a single 225 HP or 115 HP twins.

 

[mattsteg]

The 240 hp figure is based solely on a calculation based on hull geometry.

The weight of the outboard counts against the boats max. load capacity.

The closest you can get to 240 hp is a single 225 HP or 115 HP twins.

Exactly. HP capacity is primarily a hull geometry calculation (although a manufacturer can rate it lower if there is reason to).

Safe Horsepower Standards For Outboard Powerd Boats

Horsepower caculations for outboard boats with engines greater than 2 horsepower

newboatbuilders.com

Also transom thickness of 1.75-2.75 in for 75-245+HP