different type of boats with same motor

[CNT]

This is general inquiring about (tiller) aluminum fishing boats, range 12' to 16' with capably use of a 15HP 2-stroke outboard motor. The question is effects on the speed (and ride), not tiller steering. Just using below as examples.

(2020 Lund models) (svh = semi v-hull) (ips = integrated power streak)
14'1" svh @ 194lbs, max 15HP
12'1" svh @ 205lbs, max 15HP
14'6" svh @ 285lbs, max 25HP
16'2" svh @ 325lbs, max 25HP
14'2" ips @ 285lbs, max 30HP
16'2" ips @ 340lbs, max 40HP

Now, of course, to start off clearly... different boats, different results. I get it. Now, get to the point of this thread... since I have a 15HP in my basement, I am wondering if I buy a "max 25HP" boat and put my 15HP on it, would it be a drag? Would it be best if I seek a boat with "max 15HP" label, to use my 15HP? Perhaps rephrase the question, would the speed be close the same as if using a same 15HP OB on either boat, "max 15HP" or "max 25HP"? Or I should be looking at the weight factor?

Concept the same with jon boats?

1436 @ 162lbs, max 15HP
1542 @ 190lbs, max 25HP
1448 mod @ 562lbs, max 25HP
1754 mod @ 670lbs, max 50HP

Would a 1436 and 1542 result the ~same~ plan and speeding, with the same 15HP OB?

Also, while at the same weight, using same 15HP OB, would a 14'1" svh (max 15HP) and 1542 jon (max 25HP) be the same speed-ish?

I know, I need to actually start buying boats to try things. But I don't have the luxury with buying/selling cash, so I just need to make buying my first boat the best I can, most likely I would keep it (unless it's terrible and must sell). I am not interested in fiberglass boats, but I have looked at varies boats, including bass boats. The propose of this boat is for river fishing (tight to large rivers), maybe little small lake fishing.

 

[racerone]

There is more to a boat than the length of it !-------Height of the transom.-------Maximum beam ----------Depth of the hull are factors used to determine the safe HP rating.

 

[southkogs]

As you said: you're comparing apples and hippos. So, any answer here is a matter of opinion, and almost null and void when you add gear, water conditions and how often you dent the aluminum putting the boat back on the trailer

If you were to line up the SVH 14'1" with a 15HP and an SVH 14'6" with a 25HP, loaded with the same gear, driver weight, water conditions, etc., etc. my guess would be the 25HP would wind up being the faster of the two. But not what I would consider significantly. "Several" miles per hour, maybe?

Go up to the 14'2" with a 30HP, and put it up against the 14'1" with the 15HP, and I think you'll see more of a difference. But even at that - I'm not sure it would blow you away. The longer the distance, the more you'll see a reason to go a little faster. But for runs around 5 miles, I don't think it matters that much.

On the rivers down here in Tennessee, if I were in your shoes with a 15HP in hand: I'd find an open v hull with oar locks (like Lund's SVH) that'll run the 15HP. Probably right about 14'. My guess is it'd probably run about 20-25 MPH (-ish) and hold me an' a bud with some gear and lunch.

In short: I think you're over thinking it.

 

[CNT]

As you said: you're comparing apples and hippos.

​

Really? Not apples and oranges? LOL

​

In short: I think you're over thinking it.

I know I tend to over think this... only because I still haven't got any boat and my 15HP is sleeping in the basement. Anyways, perhaps I have been looking at too many boats (even from coast to coast!). There was thought provoking, which I typed in the OP, but erased it since it's OT.

So, I need to step back and look at "a boat is a boat" (to a point). layball:

 

[southkogs]

Seriously, look at how far you're going too. My longer runs are about 20 miles, typically. I do those around 30MPH in the Bayliner. At 23MPH, it wouldn't be that much longer to make the same trip. On the lake I fish the most, I don't typically run more than about 5 miles, and the boat I use barely makes 20MPH. If I can't spare the 15 minutes it takes me to get to a fishing spot ... I need to rethink what fishing is

If you're fishing tournaments, it's a whole different story. But most of us aren't doing that, and the bass don't really swim that fast

 

[Old Ironmaker]

Yep, you are definitly overthinking this thing. In my experience the only way to find what speed a boat will go with X HP engine is to take it out on the water. It isn't something one can easily quantify on paper in my opinion. A big factor to consider is if whether or not an older 15 HP tiller is actually 15HP after years of use, same goe

 

[Old Ironmaker]

Seriously, look at how far you're going too. My longer runs are about 20 miles, typically. I do those around 30MPH in the Bayliner. At 23MPH, it wouldn't be that much longer to make the same trip. On the lake I fish the most, I don't typically run more than about 5 miles, and the boat I use barely makes 20MPH. If I can't spare the 15 minutes it takes me to get to a fishing spot ... I need to rethink what fishing is

If you're fishing tournaments, it's a whole different story. But most of us aren't doing that, and the bass don't really swim that fast

We head out on Erie about 10 miles to the Walleye.. Buddy with his 250 HP Merc high tails it out there at 50MPH and leaves me in his wake in my 115 Mariner doing 30, maybe. When I get there maybe 5 mins latter he is monkeying around with his tackle. I organized ours before we wet the boats and am fishing 15 minutes before he is. So what's the point of speed beside bragging rights?

 

[ahicks]

I think the water you're on most frequently should determine your hull size and shape. If you're on a couple hundred acre inland lake only, it's hard to go wrong. Same can't be said if you ever plan on playing in bigger water, even with good weather conditions.

Define your mission the best you can, THEN buy a suitable boat. It's that easy, really.

And you can always sell that 15 if it turns out it's not suitable - or if you find a deal on a boat and motor combo.....

 

[Silvertip]

Let's look at this another way: You have three basic boat lengths and weight groups. 12, 14, and 16 ft. In each of those three groups you specify two HP ratings. So let's start with the 12 footer. That is a very light boat and it specs a 15 HP max. What you can be assured with that boat is that it will perform at it's optimum with that motor keeping in mind all 15 HP motors (Merc/Evinrude/Nissan/Yamaha, and 2 stroke vs 4 stroke etc) will not result in the same performance. Keep that in mind as we move forward. When reading performance reports be certain you are looking at the same engine manufacturer. Moving to the 14 footers, you are trying to compare 15, 25 and 30 HP engines. I once owned a light 12 foot boat with an old Johnson 10 HP motor (which was actually a detuned 15 HP) and wide open it was a scary ride. Now then -- the 14 footer hull design may actually be faster than the 12 footer but that's a big "IF". For certain, the 25 will be faster but about or nearly equal to the 30 Hp. Keep in mind that you are nearly doubling the HP over the 15. The 16 footers again will win the race over all the others with the 40HP. The 30HP and 25 HP 14 footer may be about the same. But again, you are comparing too many things (especially engine HP) to be practical. But the basic rule of thumb is whatever boat strikes your fancy -- do NOT power it with less than 75% of its rated HP or you risk owning a "slug". If the boat is rated for 40 HP max, don't put a 25 on it. It may be fine with just you in the boat but add a buddy or two and you may as well break out the oars. The other physics lesson is a small engine working it's guts out will not last as long as a bigger engine "loafing" and would likely not be any more fuel efficient because it takes more throttle to get the same amount of work done. Determine what how and where you will use the boat, how loaded it will typically be and then find your boat, THEN pick the power plant that will fill the 75% or more rule of thumb. Oh yes - the final step is go fishing.

 

[Sea Rider]

A 15 HP motor will push/plane better a tad larger boat, say a 12-13 footer than a much shorter one , provided that you use it lightly loaded say max 2 up with a maximized prop for motor to rev middle to max wot rpm range factory stated. Motor/transom height match, correct deck load distribution and trim are 3 factors to consider besides a prop maximization.

Probably won't be a speed demon but will have excellent water fun time with it.



As an example my Rib is rated for 6 and a 50 HP motor, the current motor in daily use is a 2 strokes 18 HP, the prop has been maximized, runs near 40 K/m at wot with 2 up at slight chop water cond and at 5900 wot rpm., toatl combo weight, motor and 2 boaters is 1/2 ton (Kg) Not bad for an 18 HP.

Happy Boating

 

[CNT]

But the basic rule of thumb is whatever boat strikes your fancy -- do NOT power it with less than 75% of its rated HP or you risk owning a "slug". If the boat is rated for 40 HP max, don't put a 25 on it.

THEN pick the power plant that will fill the 75% or more rule of thumb.

That's the answer to my question! Thank you.

 

[Scott Danforth]

the 14 foot fishing barge I have that Dad and I fished in for decades has a 12hp gale on it now. it could plane with 1-2 people, however any more and it would simply plow.

the 12hp wasnt a speed demon with 4 people in the boat, however it pushed the boat fine for decades.

the gale will be made into wall art, as I have a 20hp merc to hang on the back.

you really should simply pull the trigger on a boat soon and then you will learn what you like and what you want next faster than the analysis-paralysis you seem to be suffering.

since you have a 15hp, find a 14 - 16 foot aluminum boat and go boating.

 

[Sea Rider]

All boats are rated for max HP motors and max number of passengers, if you won't be boating with max number of passengers stated for that particular boat model don't need to go close to 75% of its HP rated which assume will be the Min % for Max number of passengers. In reality can go way less going towards a prop maximization to a less pitch prop to pull wot revs up. Will need to buy and install an induction tach for that venture

The issue here is that only a few boaters goes straight for a prop maximization which is a night/day boating difference as to keep boating with the motor prop it was factory delivered with while pushing/planing a larger non heavy boat.

I'm probably breaking the worlds's Rules of Thumb record regarding the Min % of the Max Rated Power as currently boating with top water performancee with 2 up with only 36% of its max rated HP motor for that boat which weights all by itself 230 Kilos (506 Lbs) which doubles the weight of all those Lund mentioned models..

BTW, what has been mentioned here works spot on for fixed light loads, variable or heavier deck loads which are rpm serial killers needs less pitch props than lighter deck loads or fixed ones.

Happy Boating

 

[CNT]

a prop maximization which is a night/day boating difference as to keep boating with the motor prop it was factory delivered with while pushing/planing a larger non heavy boat.

I am lightly aware about that, which I haven't gotten into that yet. I want to climb the ladder without skipping too many steps.

 

[GA_Boater]

A motor sitting in your basement is useless lump gathering dust. While you're dithering on what boat to get, the motor is deteriorating from lack of use.

Buy a tin boat, any tin boat with a max 15HP rating. We can't make up your mind for you. Get off the stump before it rots away beneath you!

 

[CNT]

A motor sitting in your basement is useless lump gathering dust. While you're dithering on what boat to get, the motor is deteriorating from lack of use.

​

Not so... in fact, it's SNOWING outside now (at the time of typing this).​

​

Buy a tin boat, any tin boat with a max 15HP rating.

Yeap. As I didn't share a story (typed it, then erased it since it's OT in here), THOUGHT PROVOKING. Been lookling at "tin boats" (as you call it), but with OUTRAGEOUS asking price. Some (or a lot) of sellers are asking for so much money for their used boats, while brand new are selling for less! Again, it's SNOWING outside now... in other words, boat marketing is slow, different, outrageous, cheap, whatever, at this time. Thank you.

 

[JimS123]

I never liked trailing the big family boat on vacation, but that's just me. When my boys were young we bought a 13.5" tinny with a 9.5 Evinrude. The boat was rated for a 25. The 9 planed the boat (with the right prop). We didn't go real fast, but we got there and had a lot of fun in the process.

As I look back those were the years and that was the boat we made the most memories in. As a matter of fact, I still own the boat and it will probably be the last one I sell.

After the kids grew up and I was fishing on my own, I put a 25 on her. Squirrely. I ended up with an 18.

Bottom line is: Do you want to have fun with the family, or show off and waste a lot of money?

 

[CNT]

Bottom line is: Do you want to have fun with the family, or show off and waste a lot of money?

err... OK? Here we go... all my kids are GONE. Last one is 18 now. We had our share of time and memories. The kids are now in colleges (one is becoming Dr. House, seriously, and the other is in Engineering). Alright? So, from this time forward (as quote from the Borg movie), it's ME and my wife, not including the dog. So, does that mean I am not doing the right FUN or what?

Show off... that is not in my mind, nor even crossed my mind.

Waste a lot of money... actually, I wish. but, in my terminology, wasting a lot of money in good reasons, like donations, helping my family (mother and sisters), my kids (through colleges, and some other things like cars), and buy a yacht. In fact, I would be still in the same house, while I build a humble home up north (yet three bedrooms, and in one of the bedroom would be an exercise room), with a 4 car garage (and a section for a woodshop). BUT I AREN'T GOT MONEY TO WASTE (yet). If I had "waste a lot of money" (as you call it), I wouldn't be here, I would be out fishing, with boats (with "s").

Anything else interest to know about me? Actually, should I say I have a confession to make... I just bought a car for $600. It's a steel deal (something that we would call it "no rust"). I was thinking about sharing about that in OT thread, but show off... huh?

Example... I do NOT like Dodge (don't ask me why). For whatever happened, I have a Dodge on my driveway (again, don't ask me how's that Dodge going, hint, had to replace a whole new engine, THAT was a "waste" of $7K). My BIL is a Dodge guy. He just bought a Hellcat, and still have Viper and pickup truck. I tell him straightforward, I wouldn't want to own one of these, he can accept that (not because it's his, or whatever you may think of). One time we were doing something together, and when we come to discussion (that I point out my point in good honesty), my wife asked my BIL (her brother), why he (me) doesn't like it, he says to my wife, "It's a Dodge" and we all smirk (and no one is angry).

The closest may be that I tend to like "bragging rights". Now I think that's far enough for now?

Is Mr.88 reading this too? Am I a marked person in this iboats forums?

 

[southkogs]

I agree with the 75% rule about power, but I think really in this type of boat the difference is negligible. We have a 14' fiberglass boat with a 9.5HP on it. We also have a 12' fiberglass with a 3HP on it. The 9.5 will outrun the 3 any day of the week. But going across the lake to a fishing spot, the arrival time difference is minutes.

I don't disagree someone might want more motor, more boat or even more bells and whistles. But if you have a motor you're confident in, the difference we're discussing from the original post on inland lakes and rivers is minimal. If you're on a river with a lot of flow, the extra HP might be good. But if you're in a lot of skinny water, having the smaller outboard and lighter boat may be a huge benefit.

 

[JimS123]

err... OK? Here we go... all my kids are GONE. Last one is 18 now. We had our share of time and memories. The kids are now in colleges (one is becoming Dr. House, seriously, and the other is in Engineering). Alright? So, from this time forward (as quote from the Borg movie), it's ME and my wife, not including the dog. So, does that mean I am not doing the right FUN or what?

Show off... that is not in my mind, nor even crossed my mind.

Waste a lot of money... actually, I wish. but, in my terminology, wasting a lot of money in good reasons, like donations, helping my family (mother and sisters), my kids (through colleges, and some other things like cars), and buy a yacht. In fact, I would be still in the same house, while I build a humble home up north (yet three bedrooms, and in one of the bedroom would be an exercise room), with a 4 car garage (and a section for a woodshop). BUT I AREN'T GOT MONEY TO WASTE (yet). If I had "waste a lot of money" (as you call it), I wouldn't be here, I would be out fishing, with boats (with "s").

Anything else interest to know about me? Actually, should I say I have a confession to make... I just bought a car for $600. It's a steel deal (something that we would call it "no rust"). I was thinking about sharing about that in OT thread, but show off... huh?

Example... I do NOT like Dodge (don't ask me why). For whatever happened, I have a Dodge on my driveway (again, don't ask me how's that Dodge going, hint, had to replace a whole new engine, THAT was a "waste" of $7K). My BIL is a Dodge guy. He just bought a Hellcat, and still have Viper and pickup truck. I tell him straightforward, I wouldn't want to own one of these, he can accept that (not because it's his, or whatever you may think of). One time we were doing something together, and when we come to discussion (that I point out my point in good honesty), my wife asked my BIL (her brother), why he (me) doesn't like it, he says to my wife, "It's a Dodge" and we all smirk (and no one is angry).

The closest may be that I tend to like "bragging rights". Now I think that's far enough for now?

Is Mr.88 reading this too? Am I a marked person in this iboats forums?

OK, now I got it altogether. You provided a lot of boat data, and others have said you are overthinking it. Now its clear, you want to go boating with a puppy and maybe a wife.

Bottom line is that you need to figure it out for yourself. Your idea of fun probably ain't mine. I'm happy with running 40% HP - how fast is your own personal requirement? I'm happy if it takes longer to get there because the longer it is the longer I get to have a boatride. For ME, the bigger HP and gas consumption would not be cost effective.

Butttt, after having said all of that, after all MY kids finally left the nest, I went out and bought a brand new tinny with all the bells and whistles - swivel seats, full floor, awesome sonar, etc. Guess what? The wife didn't like it - it was not comfortable enough. I suffered for a few years and then after retirement I bought a boat that SHE liked. Cost more than our freakin house. Waste of money - heck yes, but then again the wife is happy with it.

So, my final recommendation is to buy a 14' Starcraft basic V-hull aluminum utility. The 15 will push it just fine.