Member Removed Posted December 29, 2011 Report Share Posted December 29, 2011 Hi looking to change my engine i have a 50hp merc with nothing wrong and runs fine will be selling when i find a bigger one but what size can i fit its a 19` day boat that has about 2` draft I was thinking of a 75 to may be 90-hp my current engine pushes us along at 20 nts flat out and is happy about 18, the boat is older and heavier built thsan the newer ones, the boat is called carisma and was made by global sports the model is sea dog (not sea hog) any ideas thanks rupert. Quote Link to comment Share on other sites More sharing options...
Wedger Posted December 30, 2011 Report Share Posted December 30, 2011 There should be a manufacturers max hull rating. I would ask around before fitting too big an engine or you may find it hard to get insurance. Quote Link to comment Share on other sites More sharing options...
TomBettle Posted December 30, 2011 Report Share Posted December 30, 2011 There should be a manufacturers max hull rating. I would ask around before fitting too big an engine or you may find it hard to get insurance. JUst to add to Wedger's comments. You will find that any insurer will take your money and send you a certificate, but if you had a claim and the assessor found the engine was bigger than the manufacturers maximum then your insurance would be invalid. That's a pain if you have sunk your boat, it's a prison term if you have caused major injury to a third party. As for engines. I very much doubt your boat is drawing 2' unless you mean that with the engine down. Most 19' planning or semi planning hulls will draw 1' to about 14 or 16". Some may have a small skeg on them making them more semi displacement / semi planning and I guess if yours had this it could bring the overall down to 2', but unlikely. Anyway, that's by the by. IF the maker allows an engine as big and a 50 is giving you 20 knots then a 90 will give you +/-30 knots assuming the hull is a planning or semi planning hull. Quote Link to comment Share on other sites More sharing options...
duncan Posted January 1, 2012 Report Share Posted January 1, 2012 Tom's covered the what - a bit on the why... The are elements associated with the loading on the transom, both the simple force and the angular. Then there are some (old) thoughts about the simple weight associated with power units - for older models the manufacturer will have used this despite the significant power to weight improvements over recent years (and the potential difference between 2 units of the same nominal power). Where this is the only relevant original design element driving the restriction you may find the manufacturer has issued an update over any onboard plate. Then you have the power potential to drive the hull and it's design speeds. Gererally manufacturers aren't in the business of one off approvals of any increase - however appropriate. Beware verbal statements by distributors ie 'It's fine with a 75...'. Back to your original post - I would expect that a 19ft craft that has a 50 (ie it's a planning hull) should be rated to at least a 75, so you just need to research it. Quote Link to comment Share on other sites More sharing options...
Member Removed Posted January 3, 2012 Author Report Share Posted January 3, 2012 Thanks guys, my problem with the manufacturer is that i can not find any info on them, if any one knows or has or has info on a Global Sports boat model Sea Dog and she is called Carisma, thanks rupert Quote Link to comment Share on other sites More sharing options...
Coddy Posted January 3, 2012 Report Share Posted January 3, 2012 Any chance of any pics?? Dave Quote Link to comment Share on other sites More sharing options...
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