25 hp johnson on 14 ft crestliner help

[azfishnut]

I just finished this project, or so I thought a couple of weeks ago. One of the things that I noticed was that there was alot of spray and it struggle to get up on plane. I thought that it was because of the extra weight from adding the fishing deck. A friend of mine that is a fellow boat nut pointed out that the cav plate looked pretty low in relation to the keel. Upon further research I discovered that the cav plate was almost 3" below the keel. Because I lacked the transom height to raise it, I rebuilt the top of the transom to bring the cav plate even with the bottom of the keel. I haven't had a chance to test it yet, but I will be taking it out this weekend to see if that improved the performance at all. The last run, it struggle to get above 13 mph on the gps. From my understanding, this old girl should clip along at about 25 mph. Would a different pitch prop be a good idea as well? I have a 9 x 10 on there now which I believe is what came with the motor from the factory. I should mention the motor is a 1969 2 stroke. I would appreciate any input on how to improve the performance on this old girl.

 

[sschefer]

Re: 25 hp johnson on 14 ft crestliner help

I have a 18hp Nissan 4 stroke short shaft with a 9-1/4x9 (Nissan #10) prop on a 14' Western with a 15' transom. It's a perfect match. The boat with a 12 gal gas tank, dual down riggers, Minkota Terrova 55lb trolling motor and two blue top exide batteries still hits 24.5 mph on the GPS at or near sea level. At 5100 feet it drops back to about 21 mph. I should mention that I weigh 230lbs also.
So yes, If the motor is in decent shape, you should get 25mph out of your boat and a 25 should turn a 9x10 easily at low altitude. If you have a Tach you should see about 6000 rpms with that prop at 25mph.

Moving the motor up was a good move and should do the trick. Let us know how it went.

 

[jbjennings]

Re: 25 hp johnson on 14 ft crestliner help

Just my opinion:
I totally agree that a 25hp motor on a 14ft. ALUMINUM boat (is your's aluminum?) should run about 25mph with a decent load. However, I just don't think the motor cav. plate sticking 3 inches below the keel is all that bad. It's not like your boat is a 20 foot bass rig with a 200 hp on it. I would think that 1 or 2 inches below the keel is perfectly normal. Do you have a longshaft motor on a short shaft boat? If not, I don't think you'll see more than 2 or 3 mph difference by raising the motor up--at the most. It could be that your motor isn't running in the correct position. Or that the motor isn't running right.
JBJ

 

[azfishnut]

Re: 25 hp johnson on 14 ft crestliner help

I have a 18hp Nissan 4 stroke short shaft with a 9-1/4x9 (Nissan #10) prop on a 14' Western with a 15' transom. It's a perfect match. The boat with a 12 gal gas tank, dual down riggers, Minkota Terrova 55lb trolling motor and two blue top exide batteries still hits 24.5 mph on the GPS at or near sea level. At 5100 feet it drops back to about 21 mph. I should mention that I weigh 230lbs also.
So yes, If the motor is in decent shape, you should get 25mph out of your boat and a 25 should turn a 9x10 easily at low altitude. If you have a Tach you should see about 6000 rpms with that prop at 25mph.

Moving the motor up was a good move and should do the trick. Let us know how it went.

Thanks for the reply. Moving the motor up was a step in the right direction. It gave me an increase of about 5 mph. We had 2 people in the boat with it fully loaded and it got up to 18 mph. I would still like to get it to break that magic 20 mark though. The motor is in great shape and has been well maintained. My father bought this boat when I was 8 years old and I ended up with it about two years ago. My dad did not use it a whole lot, so it has pretty low hours on the motor. I had the compression checked when I got the boat and had them give it a tune up. It runs well and always starts first pull when it is warmed up. I am curious if stepping up the pitch on the prop would bump it along the lake a little better and if the motor would be able to handle the increase in pitch.

 

[azfishnut]

Re: 25 hp johnson on 14 ft crestliner help

Just my opinion:
I totally agree that a 25hp motor on a 14ft. ALUMINUM boat (is your's aluminum?) should run about 25mph with a decent load. However, I just don't think the motor cav. plate sticking 3 inches below the keel is all that bad. It's not like your boat is a 20 foot bass rig with a 200 hp on it. I would think that 1 or 2 inches below the keel is perfectly normal. Do you have a longshaft motor on a short shaft boat? If not, I don't think you'll see more than 2 or 3 mph difference by raising the motor up--at the most. It could be that your motor isn't running in the correct position. Or that the motor isn't running right.
JBJ

thanks for the reply. Yes the old girl is aluminum. I had alot of spray going all over the place with the lower setting and raising it up seemed to all but eleminate most of that. It got up onto plane much quicker than before. I think there is a bit of room for improvement yet. With all of the work I did to the interior, I added quite a bit of weight. I used about 3 four by eight sheets of 7/8 marine grade plywood and a roll of carpet, so If I am to guess, I would say about 200 pounds of wood, 2 deep cycle batteries, tackle and all the rest would be about 350. I would like to hear your thought on correct positioning of the motor. Do your me trim? I messed with the trim positioning a bit and found what I think works best with this set up. I am completely open to suggestions though. Much thanks.

 

[steelespike]

Re: 25 hp johnson on 14 ft crestliner help

The 69 25 is rated at 32 stock on a light fast boat.Of course your boat is no longer light or fast. I would raise it to a point just before venting becomes a problem just be sure it pumps water.And clamps have a good grip.Just add
1/4" sticks on the top of the transom.An inch could gain a couple of mph
The old style gearcase will limit your height some but go as far as it allows.
If you can find a prop with a little cup it would help.I would think with careful trim and weight distribution 20 to 25 may be possible.Something like a tiny tach will tell you a lot about the prop.69-76 25s are rated at 5,000 to 6,000 rpm. 9" X 10" is standard.

 

[sschefer]

Re: 25 hp johnson on 14 ft crestliner help

Thanks for the reply. Moving the motor up was a step in the right direction. It gave me an increase of about 5 mph. We had 2 people in the boat with it fully loaded and it got up to 18 mph. I would still like to get it to break that magic 20 mark though. The motor is in great shape and has been well maintained. My father bought this boat when I was 8 years old and I ended up with it about two years ago. My dad did not use it a whole lot, so it has pretty low hours on the motor. I had the compression checked when I got the boat and had them give it a tune up. It runs well and always starts first pull when it is warmed up. I am curious if stepping up the pitch on the prop would bump it along the lake a little better and if the motor would be able to handle the increase in pitch.

With all that weight, I would say you've about hit tops with that prop. In order to find the sweet spot with out a lot of trial and error you're going to need a tach from here on out. To get the best all around performance, you need to first make sure the cavitation plate is on a level plane with the bottom. You want it to act as an extension of the bottom rather than a trim plate.

Install a Tach and note the RPM's at max speed with the motor in the new position. If you are not hitting that magic 5000-6000 rpm range you have too much pitch in the prop for the load that you are trying push and you are pushing a pretty big load.

You also might consider dumping the dual batteries and going with a single AGM like the Exide Blue Top. It only weighs 35lbs, charges off the recitifier enough to keep you going (I use an onboard charger to bring it up to full) and runs the Minkota Terrova for about 3 hours trolling at 1.8 mph.

 

[azfishnut]

Re: 25 hp johnson on 14 ft crestliner help

The 69 25 is rated at 32 stock on a light fast boat.Of course your boat is no longer light or fast. I would raise it to a point just before venting becomes a problem just be sure it pumps water.And clamps have a good grip.Just add
1/4" sticks on the top of the transom.An inch could gain a couple of mph
The old style gearcase will limit your height some but go as far as it allows.
If you can find a prop with a little cup it would help.I would think with careful trim and weight distribution 20 to 25 may be possible.Something like a tiny tach will tell you a lot about the prop.69-76 25s are rated at 5,000 to 6,000 rpm. 9" X 10" is standard.

I will give it a try with raising the motor a quarter inch at a time on the next outing. Raising it up so that it is even with the keel made a signifigant difference. I have a buddy with a tiny tach that I can take along on the next run. Any ideas as to where I could find prop with a bit of cup?

 

[azfishnut]

Re: 25 hp johnson on 14 ft crestliner help

With all that weight, I would say you've about hit tops with that prop. In order to find the sweet spot with out a lot of trial and error you're going to need a tach from here on out. To get the best all around performance, you need to first make sure the cavitation plate is on a level plane with the bottom. You want it to act as an extension of the bottom rather than a trim plate.

Install a Tach and note the RPM's at max speed with the motor in the new position. If you are not hitting that magic 5000-6000 rpm range you have too much pitch in the prop for the load that you are trying push and you are pushing a pretty big load.

You also might consider dumping the dual batteries and going with a single AGM like the Exide Blue Top. It only weighs 35lbs, charges off the recitifier enough to keep you going (I use an onboard charger to bring it up to full) and runs the Minkota Terrova for about 3 hours trolling at 1.8 mph.

I am going to play around with the height a bit more. I appreciate the viusual on the cav plate acting as an extension of the hull. that helps make sense of that bit of engineering.

I understand that I am pushing a bit of weight. I may be at the max of what a 25 can do for this boat. Any thoughts on switching the carb to a 35 and reporting the intake? I am reluctant to get to excited about mods like that if it will affect the reliability of this motor. This motor is like the energizer bunny in terms of reliability.

I don't have a rectifier on this motor and I understand they can be retro, but are a bit pricey. This is why I opted for the two battery system. Time to get a tach out to see if there is any room for improvement for it as it is.

 

[jasper60103]

Re: 25 hp johnson on 14 ft crestliner help

I used about 3 four by eight sheets of 7/8 marine grade plywood...

azfishnut,
just curious. How many layers of plywood did you put down? Do you know what model crestliner you have?

Btw, I have 1977 Crestliner Voyager Deluxe 16'. Spec says it 400lbs. The console and storage locker was removed and plywood flooring was added by previous owner. I have a j25hp tiller pushing it. I haven't had a chance to try it out yet.

jasper

 

[azfishnut]

Re: 25 hp johnson on 14 ft crestliner help

I used about 3 four by eight sheets of 7/8 marine grade plywood...

azfishnut,
just curious. How many layers of plywood did you put down? Do you know what model crestliner you have?

Btw, I have 1977 Crestliner Voyager Deluxe 16'. Spec says it 400lbs. The console and storage locker was removed and plywood flooring was added by previous owner. I have a j25hp tiller pushing it. I haven't had a chance to try it out yet.

jasper

She is a 1956 14 footer. I am not sure what the model is but I think it is a commodore. I only used one layer of plywood. I tried to keep it as light as I could and still have it last for a good long time. I supported the plywood with 2 x 2 in any of the stress areas. I would imagine mine started out in the 400 pound arena.









I don't know if the photos will come through or not, but I made an attempt to attach them. Yours looks like a nice boat.

 

[Whoopbass]

Re: 25 hp johnson on 14 ft crestliner help

I like the looks of your old Crestliner. It's one of the best looking tin rigs i've seen. Kinda reminds me of a classic car.

How did you get the front deck to fit so tight to the sides? You must be some type of finish carpenter.

 

[jasper60103]

Re: 25 hp johnson on 14 ft crestliner help

azfishnut,
that's a sweet looking rig, mann. You did a great job.
Puts mine to shame. I just bought mine a couple months back though.

I checked the records. The commodore was made up until 1990. Must be a great boat.

http://www.iboats.com/Crestliner_Boats/bp/20br1130

Thanks for sharing.

jasper

 

[steelespike]

Re: 25 hp johnson on 14 ft crestliner help

Have you checked out the Retrocrestliner site.Boats catalogs logos etc.
excellent www.retrocrestliner.com I have a 57 Buccaneer 18 Short deck with a 1965 Merc 500.I,ve known the boat since new I think it was ordered no paint no logo. It is still factory original.

 

[azfishnut]

Re: 25 hp johnson on 14 ft crestliner help

I like the looks of your old Crestliner. It's one of the best looking tin rigs i've seen. Kinda reminds me of a classic car.

How did you get the front deck to fit so tight to the sides? You must be some type of finish carpenter.

Thank alot. I really liked the lines on the old girl before I committed to restoring her. I wanted to hang on to some of what I thought the craftmanship of the era she was built in stood for. So hearing that classic comes to mind means alot.

The front deck was a real project. Way back in the day I did do some finish carpentry, but that was a couple of decades ago. I putter around with a bit of woodworking now and then. I built templates out of 1/4 inch luan that I ripped down to about 2 inches wide and then assembled with hot glue after I scribed the pieces and cut them to fit on a band saw. It worked really well and most of the pieces fit first try with about an 1/8 inch gap at the most. It was a challenge as this boat does not have a straight line anywhere and every thing had to be fit that way.

 

[azfishnut]

Re: 25 hp johnson on 14 ft crestliner help

azfishnut,
that's a sweet looking rig, mann. You did a great job.
Puts mine to shame. I just bought mine a couple months back though.

I checked the records. The commodore was made up until 1990. Must be a great boat.

http://www.iboats.com/Crestliner_Boats/bp/20br1130

Thanks for sharing.

jasper

Thanks Jasper. I am really pleased with the way it turned out. I knew the boat pretty well as my Dad brought her home when I was about eight years old. I used to daydream about what I would do if she were mine. With the way the weight is distributed makes it about the most stable small craft I have ever been on. It helps when you have good bones to start with. Crestliner sure didn't skimp on the gague of Aluminum they put in their boats back in 56. Good luck with your boat. Should provide alot of enjoyment.

 

[azfishnut]

Re: 25 hp johnson on 14 ft crestliner help

Have you checked out the Retrocrestliner site.Boats catalogs logos etc.
excellent www.retrocrestliner.com I have a 57 Buccaneer 18 Short deck with a 1965 Merc 500.I,ve known the boat since new I think it was ordered no paint no logo. It is still factory original.

Yeah I have been on that website. It was helpful when I was trying to reasearch what year mine was. I was a bit surprised to find out the age. I would love to see some pics of your buccaneer. I kind of got hooked on these old tubs.

 

[steelespike]

Re: 25 hp johnson on 14 ft crestliner help

Unfortunately shes burried in the garage.I rode in her when she was new w
a 57 35hp Johnson. original owner took excellent care allways under cover or inside.It was used for duck hunting hauling trash, people and luggage and a stand by fire boat.I bought her about 5 years ago.I think the Crestliners come closest to the Wooden boat shape of the era.Look good with few handling faults.