New-To-Me Short Toon...Setting Up Questions

[Muddy Bottoms]

New old guy...first post here. Guess this is my intro so "Hey" to the iB'ers. Read this forum a lot being linked here many times from other places on the interwebs. I'm not always this windy so bear with me. I'll do better.

Having owned several various configs of watercraft over the years, I'm not totally lost in the discussion. But, having said that, I didn't sleep at a Holiday Inn Express last night nor do I claim to know a lot about rigging & setting one up. All previous boats have been purchased as a setup unit either from dealer or PO. This is my first time around setting up a boat (toon) from the engine install/remote control, cabling, fueling, etc. So I have questions. I think I have a few answers but mostly questions.

After 6 decades on this planet, I went looking for a small pontoon...specifically a 16 footer...for my best all around use. That use is mostly for fishing and to narrow it down even more...night fishing for crappie, etc in a couple local lakes here near me in the Bluegrass. I finally found one...an '07 Avalon 16' Catalina. It was sitting on a newer model Tennessee trailer with added loading guides and oiler hubs and upgraded tire package. The history of this lil toon was...it was bought new by an older couple to leave in the lake in their community lake. The small lake was electric only. It had no outboard ever installed on it. It did have a Lenco Troll N Tab set up which utilizes a Motorguide 2 hp 24 volt trolling motor mounted to an actuator that raises & lowers the motor in position. There was a steering set up using a normal Teleflex cable with a few custom mounting parts to make it steer from the helm. The mooring cover had been neglected and allowed weather in & under. Carpet was toast. I saw thru the mildew, etc and determined this was a project I could handle & might even make a nice small fishin toon from what I saw. Paid her $$$ and away I go.

Searching for a small outboard, I wanted a 4 stroke. Preferred the Honda for my own reasons. Found a BF25 at a local boat tech's place that he had just gone through...comp check, carbs, filters, oil, gearcase, etc. Paid him $$$ and away I go again. Link here led me to info on measuring cables for throttle & shift. I got a remote control box with the outboard but no cables. Already had the steering cable from the old electric set up mentioned earlier. That all worked & hooked up like a charm. Ordered cables and installed. Remote control warning LEDs not lighting and the warning buzzer did not sound so after determining the old ones were defective, ordered & installed new ones. Ouch on the lights. New 6 gallon fuel tank and new hose, primer bulb. Little bit o StarTron in the gas and dunked it in a big tub of H2O. Lifted the choke and hit the key...it fired and idled like a brand new one...hardly turning a full turn. Very surprised at how quiet the little 25 horse Honda was. All is good for now.

Took the toon out for a test on Mom's Day. All worked well except for my perception of how the 25 horse should push the pontoon. I wired the tach up according to Honda's wiring diagrams for the remote control (gray wire to send) & I got 4500 rpm at WOT. Engine felt like it was not opening up all the way. Not knowing how the small 4 stroker should sound at WOT, I was going by the sound of all my previous outboards (2 strokes). Big diff in sound & response but that's not a prob. This just didn't sound/feel like it was opening all the way.

If you've read this far, I'm going to break this up into the next post where I'll ask a question or 2...or 3. See if I can get some sage advice & save myself some chasing around.

 

[Muddy Bottoms]

First question I might ask...what might a general "top" speed be for such a set up?

16 foot dual pontoons with 23" tubes. Does have full rear lounge and sunning lounge, bimini top, 2 fishing pedestals up front.
Avalon's site puts this in about 1300 lbs?
Honda BF25A long shaft
9 1/4 x 12 prop
6 gal fuel
3 people
3 batteries
Cooler & gear...no anchors or other weight...I was just out to check the engine this first time.

Speed was neglible. By that I mean by my GPS...8 mph. An old dude in a pedal boat was gaining on me before I ducked off into a cove to defer being embarrassed by being overtaken. Almost.

Now...my beginning thoughts are...maybe my new throttle/shift cable install is not allowing full throttle? I removed the engine cover once back home and re-checked the movement from neutral to WOT. I do have a slight bit that adjustment could maybe get a bit of travel to the stop. Just wondering if that small amount of travel could affect it that much. I'll tend to that but I don't see it giving much more.

I do have the engine sitting mounted down on the transom top and it seemed to be very low in the water while underway. I imagine this could be some unnecessary drag and could look at raising it up a bit. I do not have tilt/trim and the motor is pinned down in a position I guesstimate as being perpendicular to the angle of the extended transom. This Avalon has what I am referring to as an extended transom just because an earlier older pontoon I owned had a transom constructed differently and tucked in closer. Maybe re-pinning and positioning the motor out a hole or 2 might help.

I'm going to get another prop but only after getting satisfied the other couple points above are attended to. I may have to venture over to the prop section & inquire over there. I've read a lot about propping but most folks are of the higher HP crowd than my little toon and there's not a lot of mention about my application. Just cause it's a smaller set up doesn't mean I can just ignore it. I would like to make it correct & don't want to be lugging the little Honda around leading to it's early demise.

OK...I know we're not expecting much speed from a 25 on a 16 foot pontoon. I don't usually have far to travel from my launch locations to get where I'm going & that's why I opted for a smaller HP 4 stroke...economy, quiet is what I was after. But I also like it right. Now it doesn't seem...well...right.

Some images in next posts.

 

[Muddy Bottoms]

Here's a shot b4 I re-did the floor after I towed her home.

 

[Muddy Bottoms]

Doing the floor

 

[Muddy Bottoms]

New carpet. Debated the tile, carpet thing. I wanted tile or something else...SWMBO wanted carpet. See who won out.

 

[Muddy Bottoms]

My electric kicker "up" & Honda BF25. Looks like the Honda needs raised on the transom?

Kicker in down position

 

[Muddy Bottoms]

 

[Muddy Bottoms]

 

[Muddy Bottoms]

An after re-do shot

 

[rogerwa]

First off I would say that your motor is mounted too low. I would raise it up a couple of bolt holes to have the anti-cav plate just under the bottom of the transom. Adjust it as necessary to where it is as high as possible without ventilating. Then see where you are at with WOT compared to rated WOT. I don't know what the WOT rating for that motor is, but if you are low, you will need to drop pitch to get the RPM's up. You should gain RPMs by raising the mounting of the motor so do that first..

 

[HotTommy]

First, nice job with the boat. It looks great. ... Second, pontoon boats are slow and a 25 HP motor seems very small to me. .... Third, even if you get the engine height and prop speed adjusted just right, a wildly optimistic 50% increase in speed would take you from 8 MPH to 12 MPH. My intuition says 1-2 MPH is more likely. My point is that you may be better off doing whatever simple adjustments you can to optimize what you have, while not spending huge amounts of time and money in search of performance that just isn't going to be there. ... Good luck.

Second thought: An online manual for your engine indicates the rev limiter kicks in at 6,300 RPM. So it does look like you have some RPM management to play with. That might get you closer to that 50% increase in speed.

 

[ahicks]

Move that tilt pin out 1 hole to level the engine a little as well.....

I second the "nice job" mentioned already.

 

[lmuss53]

How about a picture of it out of the water from the other side? I'd like to see the motor height in relation to the bottom of the transom pan, also can you get a pitch number off the current prop.

Plus one vote for nice fix up job.

The 25 is not going to be a speed demon. Typical Wide Open Throttle top speed on an 18 with a 50 hp is about 20 mph. I would get the motor at an appropriate height for the transom (cavitation plate about level with the bottom of transom pan) and prop the motor to run in the top couple hundred RPM of the range, about 6200 or so and the speed will be what it is.

It is important for the engine to run in that range at WOT, kind of like the gearing in your car letting it run in a good rpm range at cruise speed.

 

[lmuss53]

Somehow I didn't see that side shot, I would raise that motor a couple of inches at least. I would want the water to flow off of the bottom of the transom pan an inch or so above the motor cavitation plate, and the motor about on a level plane with the bottom of the tube or out a little bit.

 

[Muddy Bottoms]

Thanks everyone.
I will raise the little motor.
Pinned it out 1 hole.
Current prop is 9 1/4 x 12
Also checked to see if tubes had any water in them. None in either side.

Yes i assumed it would be slow but thought it would do a little better than what I'm seeing.

I'll get her wet again in a day or 2 then see if the motor lift helps Rpm. Then it's on to propping. To gain 1500 RPM by pitch, that's gonna be tough is it not? Would a diameter change help too or would that hurt top speed? I understand pontoon propping is diff than other applications.

 

[steelespike]

As suggested raise the motor maybe a couple of holes ,try trimmed perpendicular to the water.
Many pontoons trim is used to minimize venting. with little other results.
You will need a 8" or 9" prop.a 4 blade should give better control and may resist ventilation better.
Your 12" is way off too big.

 

[Muddy Bottoms]

Your 12" is way off too big.

Thank you, SS. Can i assume a smaller diameter prop will also affect RPM? Gonna be trial n error with several props unless someone has a similar set up to get me close enough to start with.

 

[steelespike]

With the pontoon you need larger diameter.You will likely find that as pitch goes down diameter will go up.
A 4 blade is a way to increase blade surface.
In checking various pontoon performance tests I have noted that sometimes with smallish motors 25 to 60 hp
on say a 18 ft pontoon and a 24 ft may have close speeds with the same motor.
I have also noted that pontoons of what appears to be the same basic design may have vastly different speeds.

 

[lmuss53]

I always try to turn the largest diameter prop I can and pitch it down to get the RPM. My thinking is it gives me better control and low speed maneuverability Look around there should be 8 and 9 pitch props for that motor.

I had an 11 pitch on an OMC 90 once trying to get the cavitation issues out when I had the 90 on my Forester.

I like buying used props on ebay, you can find good props at reasonable prices and if they don't exactly work, you can relist them and not be out much more $$ than the shipping. Find the props you want on the prop search tools like here at iboats, then search ebay for those part numbers and brands.

 

[Muddy Bottoms]

I looked hard for a 4 blade 10 spline to fit my little Honda but didnt come up with anything close to what i needed. I ordered a new 3 blade 10 x 9 for 62 smackers. Probably need an 8 pitch but we'll see after i trim it out and raise the motor.