Trolling motor size for 25ft aluminum boat.

[the butcher]

I am buying a 25ft aluminum hardtop fishing boat and I am getting mixed messages from 2 different dealers. Was thinking yamaha for kicker motor. Yamaha only offers their high thrust kickers in the T9.9 and T25. I had a 9.9 kicker on my 19ft fiberglass boat and it was perfect. I feel that a 9.9 on a 25ft aluminum boat that weighs 50% more than my 19ft boat would be underpowered. I do see a number of 25ft and even 28ft boats with a 9.9 kicker mounted but feel they are likely always in the high revs to get into the right speeds.

So 1 yamaha dealer is telling me a yamaha T25 would be suitable for my boat.

Talked to another dealer, albeit it's a mercury dealer, he says that a 15hp is perfect for my boat. When I asked if the Mercury Prokicker 25hp would work, he says that he has had a number of customers on boats as large as 30ft with a meruxry 25hp prokicker mounted and they had issues getting down to speeds less than 3.5mph. The customer had to try messing arounfnwith getting different props to get slower but those high thrust props don't have a lot of size options.

Can someone tell me whether a Yamaha T25 kicker will have a difficult time on a 25ft aluminum closed cabin fishing boat when trying to dial in on the correct trolling speeds? (2-3mph).

 

[Aces]

Get the 15 hp Merc with efi. You’ll be happy with it.

 

[northwest wind]

I have a 26’ aluminum boat weighs about 8000 lbs loaded. I had this decision to make and ended up getting the 25hp mercury pro kicker. 15 might have worked 9.9 definitely not. I can troll in all conditions I have encountered and that’s the difference. 9.9 would have worked if no wind or waves. I can troll very slow was fishing rivers inlet at the head trolling.5-1 knot and could have trolled even slower if I wanted. I also don’t have the option to troll off my main engine as the slowest I can go with that is about 4.5-5 knots

 

[Buckethead905]

I have a 24ft Pursuit and just installed a new Yamaha t25. I think that would be a lot better than the 9.9, even with your boat being a little lighter than mine. If I recall my lowest speed is roughly 1.6mph. I could go slower but that is the minimum rpm I run the kicker at as it does have a slight vibration right at idle which bugs me. You definitely wouldn’t be able to go slow enough to fish rivers (if that’s even your thing, it’s not mine). As far as the 2-3mph, it would be right in its bottom 1/3 of output, which is the t25 sweet spot, very smooth and quiet, lots of thrust, and holds speed in rough weather better than I ever could have hoped for. With my autopilot and that new kicker, I fished a few times this season in 14-17 knot winds at Entrance (which is pretty ugly) and it was actually enjoyable, never had to touch the wheel or the itroll very much at all. Makes for a lot nicer day when you’re not always having to make constant adjustments.

 

[Samnjoe]

I ran a Yamaha T8 on my 28 KF. Just replaced with a new 9.9. Worked fine. Very little throttle to achieve trolling speed. Lots of power with the high thrust.
It has to be pretty snotty out for me to troll on one of my mains.

 

[the butcher]

I ran a Yamaha T8 on my 28 KF. Just replaced with a new 9.9. Worked fine. Very little throttle to achieve trolling speed. Lots of power with the high thrust.
It has to be pretty snotty out for me to troll on one of my mains.

When you are trolling on the 9.9 in your 28 KF, where in the throttle range are you at? Halfway from idle setting to WOT?

 

[the butcher]

My hull has a 21 degree deadrise. Based on the hull deadrise, where the kicker is mounted(port side of transom on kicker mounting bracket), the transom height at the location where kicker bracket is will be shorter than the transom height at dead center of transom where the main motor is mounted. That being said, is the norm for kicker shacg length to be the same shaft length as main or should kicker shaft length be 1 size shorter due to the shorter transom height at kicker mounting location? I imagine too long of a kicker shaft length will result in kicker skeg or the kicker prop to drag in water, even with kicker fully trimmed up until the boat gets up on plane.

 

[kaelc]

The new 25 yamaha is supposed to have a better trolling mode, according to my brother in law who has the old 25 as a main on a small boat that trolls too fast.

I have a 9.9 Honda on a 25.5 foot fiberglass with a galley, separate head, no fridge but 6000lbs and I rarely, maybe once had trouble trolling.

 

[InterMechanico]

Haha what’s another 20 lbs between friends??

 

[ReelSlim]

I have a 25' Aluminum and installed a Yamaha 9.9 when it was built. I'm not sure what areas you fish but I have zero issues pushing my boat regardless of wind or wave conditions. On most days it's in gear and barely need to throttle up. If you fish crazy current, then maybe the 25 is the way to go. Personally, I don't get it. The 9.9 pushed around a lot of boats for a lot of years without issues. It's still the most common site hanging off the boats in my marina including a lot of guide boats. I do have a Yamaha 25 not the HT model on a 15' SilverStreak. It will troll slow on that set up but not sure the difference with the prop and gearing on a HT model.

 

[Samnjoe]

When you are trolling on the 9.9 in your 28 KF, where in the throttle range are you at? Halfway from idle setting to WOT?

Just off idle. Not working it at all most of the time.

 

[sudsy]

I have a 26ft northwest aluminum - i went with a 20hp suzuki efi - tons of power. Suzuki 9.9,15 and 20 are essentially the same motor - if your sticking with merc id recommend the 15hp - i have tons of power with this motor and I think a 25hp would be way overkill for a trolling motor on this size boat. My 2 cents....

 

[Buckethead905]

Not at all knocking the 9.9 that’s worked for many years, there is no argument there. There are just better options available now. Few additional bonuses of the t25 are that it has a pull-start handle if your batteries die for some reason, it has a 16 amp alternator, it’s quieter, it’ll give you higher top speed if your main quits, and the rigging setup looks a lot cleaner and uses a conventional rigging tube as opposed to the externally mounted shift cable. I had the big block 9.9 on my campion 542 and the t25 on my pursuit is significantly quieter and more powerful. As I mentioned before the biggest takeaway is its ability to maintain your speed in any condition and not being wound out to do so.

 

[Fisher_dude]

24ft aluminum with a 15efi pro on it. No problems at all. What I would be concerned about is the alternator output. The bigger motors tend to have a higher output that the 9.9s

 

[ReelSlim]

Not at all knocking the 9.9 that’s worked for many years, there is no argument there. There are just better options available now. Few additional bonuses of the t25 are that it has a pull-start handle if your batteries die for some reason, it has a 16 amp alternator, it’s quieter, it’ll give you higher top speed if your main quits, and the rigging setup looks a lot cleaner and uses a conventional rigging tube as opposed to the externally mounted shift cable. I had the big block 9.9 on my campion 542 and the t25 on my pursuit is significantly quieter and more powerful. As I mentioned before the biggest takeaway is its ability to maintain your speed in any condition and not being wound out to do so.

View attachment 113618View attachment 113619View attachment 113620

They installed the same tube on my 9.9 as you have shown. However it's not exactly like the ones that connect to the flange on the big motor. It provides some mechanical protection and keeps it tidy but that's all. I ended up cutting mine back a bit. It was causing strain on the shift cable when it was tilted up and ultimately caused it to break. It was also due to corrosion but definitely ended its life early....but that lasted 5 years. The white looks good!

 

[Buckethead905]

They installed the same tube on my 9.9 as you have shown. However it's not exactly like the ones that connect to the flange on the big motor. It provides some mechanical protection and keeps it tidy but that's all. I ended up cutting mine back a bit. It was causing strain on the shift cable when it was tilted up and ultimately caused it to break. It was also due to corrosion but definitely ended its life early....but that lasted 5 years. The white looks good!

Does your kicker have the external shift arm on the side of the cowling? And same with the t25, the rigging tube doesn’t get captured at the kicker like a conventional outboard, just a zip-tie holding the two piece collar that finishes it off. I still think it looks nicer than shift and fuel lines hanging in the open.

 

[uclueletcharters]

Weight difference hanging off one side on a back corner the 9.9 HT to a 25hp will be a significant weight difference. Sure if the extra engine weight doesn't make the boat list at rest and you want to spend the extra bucks the 25 HT is a really nice trolling motor. A 9.9 HT did very well on a 24 - 26 glass boat but they didn’t have the big cabin on them like the aluminum boats that can act like a sail in the wind. Couple times a season may have to troll on main but the weather would need to be pretty wicked to have to do that.

Biggest influence in my opinion is choosing an EFI motor over carbed.

 

[ReelSlim]

Does your kicker have the external shift arm on the side of the cowling? And same with the t25, the rigging tube doesn’t get captured at the kicker like a conventional outboard, just a zip-tie holding the two piece collar that finishes it off. I still think it looks nicer than shift and fuel lines hanging in the open.

I agree it looks nicer and finished off for sure. I was just saying that it is just basically for that purpose and some mechanical protection. Depending on how it's done it can put strain on the shift cable when it's tilted up.

 

[RageWelding]

I have a 26ft northwest aluminum - i went with a 20hp suzuki efi - tons of power. Suzuki 9.9,15 and 20 are essentially the same motor - if your sticking with merc id recommend the 15hp - i have tons of power with this motor and I think a 25hp would be way overkill for a trolling motor on this size boat. My 2 cents....

View attachment 113615

Did it come with the 4 blade prop or was that an add on?

 

[sudsy]

Did it come with the 4 blade prop or was that an add on?

Had to pay the difference - i can't remember the cost but I think it was only 100$ or so.