18hp to 25hp

[870 Expressmag]

Right now I have a 1969 18hp evinrude fastwin. It works pretty good getting my 15ft meyers aluminum with a wide beam up on plane and turning or waves really bog it down but i am not a small guy either. What im wondering is, i found a evinrude 25hp from the 70's for sale. I am just wondering how much extra i am going to gain with this motor. is it worth my while to make this small of an upgrade? i been looking for a 30 or 35 but cant find one

 

[Georgesalmon]

Re: 18hp to 25hp

Its a 25% increase in power. Will make a good difference. Do you really think you need to double your HP by going to a 35?

 

[Home Cookin']

Re: 18hp to 25hp

if your 69 runs well I'd be afraid of buying new and unknown problems just for 7 HP. Unless you keep the 18 (a great motor). Maybe try another prop?

 

[870 Expressmag]

Re: 18hp to 25hp

i was planning on keeping the 18 until i figured out if i liked the new one or not. I am dont "need" to double my motor size. I am sure going up to a 25 would make a difference, however I am wondering if it would make enough of a difference to justify it. Heres the whole story. Boat is a 15ft meyers aluminum, tiller steer, 58" beam. I am 6ft 300lbs, i almost always am driving. Usually only one other passenger, either my dad at 5'9 225 or my buddy at 6ft 315lbs. i fish from back seat they fish from front. when moving they come back and sit in middle seat, i have 3 seats total. if they stay in front seat and pushes a lot of water and will get me wet, more with my buddy than with my dad. when they are in middle seat i can get boat up on plane, but it takes a bit, and anything such as a little chop or turning, etc brings it right back down. there is a small counter weight under front seat in compartment, not sure of weight, that previous owner put in there for whem he drove by himself. it cant be more than 25-30lbs. i would just like to be able to get up on plane a little quicker and easier and not have things like a little water chop or turning to bog it down and start pushing water. the current motor is a 69 evinrude 18hp fastwin 18902b with a michigan 16 prop on it. this motor was just tuned at a evinrude dealer. the motor i found is a johnson. the info the guy gave me was he bought it brand new in the 70's and used it a couple seasons then stored it ever since. he says it starts up and runs good. pictures appeared as he stated, like new. the numbers he gave me were 25r74m e4010198. the asking price of johnson is very fair and it is pull start. any help is appreciated

 

[Howard Sterndrive]

Re: 18hp to 25hp

I have a 75 20HP Evinrude, and two 25 Johnsons (73 and 75)

I notice no difference in power in the 3 motors.

The 18 might be a different story but the 20 and 25 sure seem like the same machine to me.

 

[870 Expressmag]

Re: 18hp to 25hp

thats what i was afraid of

 

[64osby]

Re: 18hp to 25hp

870, I don't think you'll see much improvement in going to a 25.

Food for thought - What is you boat capacity?

I have a 14' tinny that's rated at 765 lbs.

You and your fishin' buddy, plus a 80 to 100 lb motor. Add a 30lb weight, fishing gear, gas, anchor and a cooler.

You could be pushing 800 lbs. Depending upon your current capacity, maybe you should be looking at a bigger boat or one that has more capacity.

A boat with more capacity will ride better and should not be subject to the effects of a wake or wave. Yea it might require, or come with a bigger motor. That would be a good thing.

 

[870 Expressmag]

Re: 18hp to 25hp

well as far as a bigger boat, i really like this boat, and i bought it because of my price range, and that it gets into the smaller lakes around here where our 20ft sea-ray wont. i am not sure on what the boat is rated for, on my research the boat doesnt have a data tag and it's probably old enough it never had one. so as far as rated hp and weight capacity, i am not sure. I did the calculation i found online and it came up with something like 31hp, and thats figuring it with tiller steer, which it currently is. but the boat originally had steering wheel on second seat but all that has been removed by previous owner

 

[64osby]

Re: 18hp to 25hp

870 - doing a rough calc on your boats weight capacity.

15' x 5' = 75, 75/ 15 = 5, 5 x 150 = 750lbs.

IMO the performance of you boat or lack of is because you are at your maximum capacity.

How does your boat perform with just you in the boat?

 

[870 Expressmag]

Re: 18hp to 25hp

one day my buddy had to use the bathroom so i dropped him off at the dock and made a spin by myself, it ran quite nicely but still lacked power on turns and in chop but it came up on plane much much quicker. Thats why i thought maybe a little extra power would keep us there. i dont worry to much about the boat, we have had 3 adults in it fishing with no problem, but that was on a no wake lake so we just trolled around. heres a pictures of the boat in question, only thing different from this picture to now is i mounted 3 boat seats on swivels and then to 3/4" plywood and bolted them to the bench seats

 

[pootnic]

Re: 18hp to 25hp

Like someone already posted,it's around a 28% increase.Maybe it will be enough for what your looking for but don't expect miracles(2 mph faster but maybe better take off and planing).Both outboards in question are older(crank rated) and their hp's may be even smaller then what is listed.A newer 25hp(83 and up?),would give you a prop rated hp and most likely the performance your looking for.

 

[82rude]

Re: 18hp to 25hp

if you can get acess to difernt props try going down a couple of pitches if i read your post correctly a 16p sounds a little high for a 18hp with 2 big guys in it.i would be thinking a 10p or 9 p.those motors normally had a range of 7p to 11p.a tac would be real handy in this case.my 18 has a 10p prop and it was on a wood boat.

 

[64osby]

Re: 18hp to 25hp

870 - It's a great looking boat. I think I remember looking at your posts when you were picking it out.

The other motor might just give that little extra like pootnic said.

Props ??? I don't have a clue.


Go fishin' and have fun

 

[870 Expressmag]

Re: 18hp to 25hp

so i'm guessing the smaller the number the less pitch in the prop? if i went down i wouldnt get as fast of speed but would keep rpm's up easier, therefore maybe getting on plane and keeping it easier, am i thinking correctly?

as far as the 25hp, i know it's 25% more which when you think about it is quite a bit, the motor is like brand new and reasonably priced, however my 18 is elec start and the 25 is not. but i hate to spend the money and then not see any difference as some have said

 

[pootnic]

Re: 18hp to 25hp

I wouldn't be to sure that current prop you have is a 16 pitch....seems pretty high.
If it were a 16 pitch,I doubt you would get on plane even by urself and gear;I'd say to swing a 16p a 40hp(probably higher) would be mininum.(IMO)

Tiss the season to buy outboards,theres know rush,wait for a newer 20-30hp and be happy.

 

[870 Expressmag]

Re: 18hp to 25hp

well heres a picture of the prop hub, i just took it off, i'm assuming that number is the pitch right? not sure what P.J is though

 

[Howard Sterndrive]

Re: 18hp to 25hp

that 16 is not the pitch. The highest pitch ever made for the 22 CID motors was a 12P.
If no googlable numbers, take it to a prop shop to be measured. My 25HP on an 11' inflatable can't even run a 12P. It'll run an 11P with 1 person and a 10P with 2 people.

You want an 8P. If that's a 10 or 11 on there now, you will notice a big difference going to an 8.

Better yet, get a tinytach and make sure you're propped for 4500 to 5000 rpm at WOT, but 8 will almost certainly be the right one for an 18 pushing 3 adults.

 

[870 Expressmag]

Re: 18hp to 25hp

ok heres what i found, according to this:
http://www.go2marine.com/docs/mfr/michiganwheel/michigan.pdf
i am running a 10 pitch, and they recommend for my size motor and boat, to run a 9 pitch. Will one pitch make that much difference?

according to the chart i would be looking for a PJ 19 for a 9 pitch, if i have all this figured out correctly

 

[Howard Sterndrive]

Re: 18hp to 25hp

on these little motors, an inch is a bigger deal than you would think. I think you'd notice quite a difference going to a 9.
I still say 8P for 3 adults in the boat though.

 

[870 Expressmag]

Re: 18hp to 25hp

When I said that weight under the front seat can't be more than 25-30lbs I obviously lied, I just removed it, barely. It was wrapped in a towel, it attracts a magnet, is 20" long and 4x4" square and I haven't weighed it yet but wouldn't be surprised if it goes 80lbs