Just bought an aluminum bass boat and it is slow

[Whoopbass]

I just bought a 1997 Crestliner tournament 1750 aluminum bass boat. The boat is a tad over 17' long and is a v-hull. I think max HP is 140. It has a 1996 Johnson 4 cyl 115hp motor with a 14 x 19 aluminum prop. According to the web the hull weight of my boat weighs roughly 1150 pounds.
I took it out for a test run yesterday with about 1/4 tank of gas, two batteries and not much else. Two other guys came with me. We all weigh about 185 pounds each. I could not get the boat past 4500 rpm and that was achieved when I had the trim just right. Not sure of the speed but it seemed rather slow around 35 mph. The motor ran fine so I doubt that is causing my issues. Hole shot sucked as well.
I plan on raising the motor a hole or two and see if that helps. I also plan on upgrading the old "light" 12v motorguide TM with a heavy Minn Kota Maxxum 24 volt motor so that swap is going to add at least 100 pounds to the boat. Most of the time I will only have one passenger so with the new trolling motor and extra battery as well fishing tackle, cooler, and more gas in the tank the boat will be heavier then this last test run.
If I can't get the speed in the low to mid 40's i'm gonna sell this sucker. I remember my FIL had a 1993 17' Ranger with a 115 carbed Merc that would do 52 mph.
So I need a new prop but i'm unsure of the pitch and diameter I should get. I will most likely go with a SS prop. Help!!!!

 

[jestor68]

Re: Just bought an aluminum bass boat and it is slow

A visit to the Evinrude site indicates (in their 115 test reports) on boats similar to yours, most were running 17 pitch Viper props.

You might try yours without the extra bodies and see what it does. Buddies can make a big difference in performance.

And find a way to measure GPS speed to make any sense of the results.

According to Boat Test, a 1750 Crestliner powered by a 115 Yamy did 42 mph. Your Johnson ought to do similar, unless it's down on power(compression).

 

[steelespike]

Re: Just bought an aluminum bass boat and it is slow

It does appear you have more than a prop issue.Could be as simple as the throttle not opening all the way.
As far as the fils ranger I think the hull is probably faster than the Crestliner. Also any speed not by gps should be suspect.
A compression test should tell you the motors health.Note the condition of all the plugs as you remove them.
Lots of people don't realize an outboard is down one cylinder except for the lack of power even if its only a 2 cylinder.

 

[Whoopbass]

Re: Just bought an aluminum bass boat and it is slow

I did a compression test before I bought the boat and all four cylinders were in the 115-125 psi range. The plugs were perfect in color and wetness. I'm sure its running right. If I can get 42mph and a decent hole shot I will be happy.
Anyways, do you think a 13 1/4 X 15 SS Michigan Rapture would work? According to what i've read on the net I should pick up 600-800 rpm's with a SS prop of that pitch. (maybe more because of the width) versus whats on the boat now. Or would a 13 7/8 X 17 SS be a better choice. Both of these props are used that I can afford now.

 

[BonairII]

Re: Just bought an aluminum bass boat and it is slow

Doesn't sound like a prop issue to me. Are all cylinders firing properly(drop test and/or put a timing light on each cylinder)? Timing advancing properly?

Does boat sit low in the water(waterlogged)?

Start with the simple stuff first....throwing parts at your motor(i.e. a new prop etc) can be an expensive and unsuccessful endeavor.

 

[H20Rat]

Re: Just bought an aluminum bass boat and it is slow

So... A quick google image search of your boat, and from what I see, that is not a bass boat hull design. Bass boats in the traditional sense are racing hulls that happen to have rod holders on them. A bass boat hull has a flat area (ride pad) that is the only part contacting the water at speed. Your hull looks like it has no ride pad and maintains the V. (could be wrong, just going on an image search, but I imagine it would be tough to create a ride pad in a metal hull...)

35 mph on that hull with 2 people on board is pretty much in the expected range. The boat test number above of 42 mph was most likely one person, and a new engine, and no fishing gear. Dropping to a 17 pitch will help, but don't expect miracles.

 

[Whoopbass]

Re: Just bought an aluminum bass boat and it is slow

Here's pic's of the boat. The hull looks fast to me. The people I bought it off of inherited the boat. I told them I was there to look at their aluminum bass boat and the woman told me the boat was fiberglass. A quick look under the boat confirmed it was aluminum but I did not bother to inform her. Thank goodness they only took the boat out a couple times in 5 years of ownership cuz they didn't know much about boats. However, they did have their neighbor winterize the boat and put stabil in the tank.
I checked and made sure both carbs are open up fully during WOT and they are. The outboard runs flawless its just a slug. I did find a little info on the net about the boat with 115's on the back and it appears high 30's low 40's is the norm for this boat. I ordered a 13 7/8 X 17 SS prop. I will report back with the results. It will probably take the Seller a week to get it to me.

 

[Mi duckdown]

Re: Just bought an aluminum bass boat and it is slow

Pics could be deceiving, but it looks like you have long shaft motor on short transom.??? that whale tail should be even with bottom of the boat.?? Never seen a transom like that, stepped down. Something is wrong.

 

[Mi duckdown]

Re: Just bought an aluminum bass boat and it is slow

Just googled crestliner and there transoms look Just like yours. But your motoris 5 inches Too low if the Pics are correct.

 

[Expidia]

Re: Just bought an aluminum bass boat and it is slow

Ya, it's hard to diagnose by a back pic. Take a shot from the side. From the pic it does as the other poster just said look like the cave plate is way low so you are dragging a lot of motor thru the water. The whale tail would be the first indication to me that the previous owner had issues with performance. I'd first loose the whale tail and if the side pic shows the cav plate low i'd raise it up two holes as you planned. I raised mine up two holes after picking mine up new and it was like night and day. I bet you are throwing a lot of spray like mine was. Hardly any spray now after I moved mine up. If whale tails solved issues then the motor manufacturers would install them OEM. They just tend to cover up a bad setup. You said funds were tight but save up a few bucks and think about adding dash controlled or automatic trim tabs. The auto ones are easy to mount yourself.
They are going to make rig handle a lot better especially for hole shots as you change loads like how many in the boat on a given day. Nice rig by the way congrats. Crestliner makes a top of the line aluminum. Nice find
if speed is so important to you than think about trading up at some point to a bigger and maybe even lighter motor. That boat would probably fly with a max HP unit on it. Many Boaters love Johnsons especially one that runs great it could command a nice high sale price. An 18 year old 4 cylinder is probably heavier than the later models. I know I first had a 2006 40 4 stroke merc installed (which I had the dealer take it back after two weeks) and the exact same motor a 2007, was 30 lbs lighter! My hole shot to plane is like 3 feet with two people! The first motor took like 500 feet .

 

[Whoopbass]

Re: Just bought an aluminum bass boat and it is slow

The motor is correct for the boat although I do think its a tad low. I plan on moving it up two bolt holes and see how that does. The whale tail is coming off. I hate those things unless they're mounted on inflatable boats.
Speed is somewhat important so long term I don't know if this boat is going to work out. Last trip out the boat had the feel of a Bayliner pleasure boat at wot instead of a bass boat. My black/silver Gregor aluminum boat which is in the background of a couple of the pics would smoke this boat for at least the first quarter mile and possibly out run it all together.
If this boat doesn't work out I believe I can get back the $5400 that I paid for it. Now if I update the trolling motor, electronics, and batteries I will probably lose some cash.
Thanks for the help. I will update this with the results when I get the new prop and test run it.

 

[steelespike]

Re: Just bought an aluminum bass boat and it is slow

Removing the whale tail and raising the motor could easily net 2 or 3 mph and some rpm.
Of course the prop will help rpm as well.

 

[midcarolina]

Re: Just bought an aluminum bass boat and it is slow

That is a great looking boat you have there......... but that hull design is not a ( speed ) hull.....But that does not mean you should not be getting much better performance from her...

I agree with others observations that the motor appears to be way low......Raising the motor vertically to the correct position will make a big improvement in performance....of coarse how big improvement depends on how low the motor is now...

I would measure from the AV plate to the bottom of the boat and see if you can pick up the motor that much just using factory holes, if not a jack plate may be needed to fix the issue

 

[Bob_VT]

Re: Just bought an aluminum bass boat and it is slow

I have been through the exact same routine. You need to evaluate your spark. The numbers you posted are indicative of a dropped cylinder. I had the same exact problem with my V4 and it turned out that I had a powerpack that was throwing an intermittent signal and I was not running on all 4 cylinders.

Get an inductive timing light and at an idle watch the spark light in the lens. You will see a steady signal flash (or you should) and if you have a weak spot then the flash will be weak or on and off. If it is weak and on and off.....swap the coil to another cylinder and see if the problem follows. If the problem follows then you have a faulty coil....... if not then you need a powerpack.

Your boats performance can not be compared to a Ranger since fiberglass hulls are faster however, it can be compared to other aluminum hulls. My old 18' Fisher GT Bass boat (115 Mariner) would run 42 mph with 2 people and loaded.

 

[smittylv1]

Re: Just bought an aluminum bass boat and it is slow

Nice Boat....looks like a Crestliner Fish Hawk with bass type casting decks. Deep V hull design should handle rough water quite well...more like a walleye boat.

 

[anzomcik]

Re: Just bought an aluminum bass boat and it is slow

I have a 96 fast strike 115 on my ranger 681C (kinda similar hull shape but my boat is glass) I had a 14x19 aluminum prop and the boat was a dog, upper 30'smph, I cant recall the RPM but lower the WOT range by a little.

I put on a 13.25x17 SS and WOW different boat, dropping the 3/4 inch on the dia and 2" pitch and going SS I am pegged out at 45mph gps and 6K. its perfect. Defiantly stay away from that larger Dia. props stay with low 13" dia.

 

[Whoopbass]

Re: Just bought an aluminum bass boat and it is slow

**UPDATE**
I raised the motor two holes and took it back to the river with the same load as before. The boat performs so much better now. I picked up 400 rpms and the spedo said 40 mph. I don't know exactly how fast it was going but it was a lot better then before. Hole shot was better as well. When I get my new 17 pitch prop hopefully I will get a few more mph's out of it. This boat might be a keeper.

 

[WIMUSKY]

Re: Just bought an aluminum bass boat and it is slow

Cool! Thanks for the update.......

 

[steelespike]

Re: Just bought an aluminum bass boat and it is slow

Isn't it great when you can pick up some speed free?
Sounds like your on your way.

 

[Whoopbass]

Re: Just bought an aluminum bass boat and it is slow

Yeah, free speed is great. Not sure why it was rigged it at the factory like that.

Anyways, got the new prop today, installed it, and took it back down to the river. With the 17 pitch OMC SST prop the rpm's reached 5400 and topped out on the speedo at 42mph. Hole shot was very good. I am pleased with the boat.
Thanks for the help.