thinking about a repower

[tkrrox]

i just bought a 89 18' sea ray with a mercury 135 on the back...it runs about 45 full go...(it is in shop now for seasonal tune up so it may run a little better) the max suggested for the hull is a 175...i have seen a lot of 200's for sale and was wondering if 25hp would make that much difference as far as rating...also do you guys think this would net me enough performance to make it worth while?

i am curious if the mph gain vs the gph loss would be worth it.

thanks.

 

[crablegs]

Re: thinking about a repower

If the plate says 175, put a 175 on it. That is all you are going to hear from everyone on here, there is about ten of these threads a day. If you are getting 45 mph out of it I think thats great!

 

[tkrrox]

Re: thinking about a repower

sorry i didn't realize this was such a common question i searched it but not enough i guess. people don't build up or modify transoms to repower on this site? also...if i run a 175 with a 12'' stand off does it not effectively change my weight ratios and require the transom to be braced???

 

[Bob_VT]

Re: thinking about a repower

We stay within the USCG limits or if there is an accident.....you are toast when it comes to the law.

If max is 175 then that is max. The true question is what are you looking for? Speed? Power? If you want a 200 which will eat more fuel then get the boat that goes along with it.

 

[tkrrox]

Re: thinking about a repower

We stay within the USCG limits or if there is an accident.....you are toast when it comes to the law.

If max is 175 then that is max. The true question is what are you looking for? Speed? Power? If you want a 200 which will eat more fuel then get the boat that goes along with it.

i am looking for more speed...i like to go to lakes that are bigger and when i do trips i would like cruising speed to be around 45 not WOT is 45...seems to me if i am at WOT with the 135 then with a 175 or 200 i would be using less gas at the same speed...

is this theory incorrect...

thanks...i'm not looking to be illegal, as i am new to boats and this is my first one...(when i bought this boat the guy swore up and down it was a 55mph boat...i was just trying to make it be)

 

[dingbat]

Re: thinking about a repower

A boat max. horsepower rating has nothing to do with the transom.

You need to multiply the length times the width of your boat in feet and decimals of feet. Assuming it has at least a 20 inch transom and remote steering. Example: 18.5 ft. x 7.33 ft. = ~135.6 x 2 = ~271 minus 90 this would give you a rating of 181h.p.

 

[Bamaman1]

Re: thinking about a repower

+1 on what was said above.

 

[tkrrox]

Re: thinking about a repower

okay...so by doing the math 18.66 x 7.5 x 2 = 279 - 90 = 189.90

so i should be well within legal to put a 175 on it.

now back to the original question...will going from a 135 to 175 give me a noticeable increase?

i am wondering if the cost of repower verses the outcome would be worth it...if it doesn't net me 10mph difference than i don't think it would be worth it.

also as i stated above...is my logic on running my current 135 at WOT=45mph vs a 175 at 45mph which one would get better mileage...

thanks guys i do appreciate it.