1989 Harris Flotebote 240

shardy217

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Jun 21, 2010
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48
Hey folks,

I’m in need of help. I purchased a 1989 Harris-Kayot Flotebote 240 last year and finally got around to fixing her up. It came with a 35HP Force motor that seized up on my maiden voyage!

I recently purchased a 1990 Suzuki 90HP motor to put on it but I’m not certain if the boat is rated for it. The USCG sticker on the helm was faded and I tried recovering the info (white crayon, highlighter, a couple other things I read online) but am getting nowhere. I contacted the manufacturer a couple weeks ago with no luck as well. I checked some websites that have the HP ratings for the Harris model boats but there’s no model (sun cruiser, classic, etc.) posted anywhere on the boat or the title. The pontoons are 20” diameter and the transom is wood (I attached pictures). It also appears the transom itself is only bolted to the undercarriage with 6 bolts.

I was was hoping for some input from you guys! Do you think this boat could safely handle 90HP (400lbs) or should I sell this and get something in the 50-60HP range. Let me know what you think. Any and all feedback is greatly appreciated - I’m at my wits end!
 

shardy217

Seaman Apprentice
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Jun 21, 2010
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48
A little update - we made out the words “Classic” on the front of the boat - so I suppose it is a 1989 Harris -Kayot Classic 240
 

sphelps

Supreme Mariner
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Nov 16, 2011
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11,475
Pics might help .. i have seen a formula for a regular type boat to get a good idea on hp rating but not for a pontoon ..
Maybe post the question over in the toon section ...
 

shardy217

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Jun 21, 2010
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Sorry sphelps - I thought the pics were uploaded. Is there a way to move the thread over? I’m a newbie so I didn’t even see the toons section :boom:
 

shardy217

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Jun 21, 2010
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67EC8378-1EC7-4881-8DC3-905E255C3FF1.jpeg
 

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ahicks

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I would not put a 400lb engine on a boat like that. It's going to really weigh the back of the boat down. Nobody ran engines that size and weight back then. The boat's wouldn't handle them.

If you want to try it anyway, I would reinforce the engine pod with the addition of another cross member in the back, doubling up the one that's there.

Nice looking project. Best of luck with it!
 

HotTommy

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Mar 15, 2013
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I'll describe my experience and then offer some opinions. The engine pod and transom on your boat resemble the one that was on my old pontoon boat when I bought it. It supported a 90 HP engine, but had a crack in an aluminum weld where the transom met the side of the engine pod. I had a welder repair the crack and I replaced the plywood transom and ran that way for one season. .... I found the boat slower than I wanted and purchased a 150 HP old motor for it. I was not confident the engine pod that had cracked under the demands of a 90 would hold up, so I located a much stouter pod at a used boat parts yard. I installed that pod and reinforced the mount by adding aluminum L-beams that ran from log to log like the original support beams. I placed them as far aft as possible to deal with the added weight of the 150. I ran that combo for one season until the engine died. I replaced it with a new 115 HP and have run it with no issues for two seasons.

Now for some opinions. I suspect that any 24' pontoon boat of your era was designed to handle more than 35 HP. I suspect 90 was the usual. So if a close inspection of the pod and support beams looked OK, I wouldn't hesitate to hang a 90 on it if it were my boat. But I'd check it frequently during the season for signs of trouble.

If I wanted to play it extra safe, I'd reinforce the pod and transom. To better understand how, let me describe the forces that are applied there.
  • When you hang a motor on the transom, the weight of the motor is pushing straight down along the strongest axis of the transom, so as long as the wood is thick enough and not rotten it should be alright. The transom is pushing straight down on the pod at all the points where they connect. That can be a weak spot. The engine pod is pushing straight down on the support beams, but because there are no beams directly where the engine sits, most of the weight is on the beams farthest aft. For reasons that are too technical to describe here, the downward force on the aft beam may be more than the total weight of the engine and pod. That is why I added beams as far aft as possible on my new pod.
  • When you add power to propel the boat in the water, the propeller pushes water aft causing a forward force on it. That force is carried through the engine to the transom and then to the pod. Assuming the transom is sufficiently strong and the connections between it, the pod and the support beams are normal, that force is not too extreme. But the engine also produces another force.
  • Because the propeller is at the bottom of the engine and the transom is much higher, the bottom of the engine is being pushed forward while the boat is resisting movement by pushing the top of the engine aft. That create a torque (a twisting force) that will try to pull the top of the transom aft while pushing the bottom of the transom forward. It is sometimes called the can opener effect after old timey manual openers. To deal with this issue I fabricated a 1/4" thick aluminum plate about the size of the transom and used it as a backing plate. It was held in place by the same bolts that secured the engine to the transom.
Lastly, if you are not confident in your ability to judge the serviceability of your boat, try to locate an experienced boat mechanic locally to look at your setup. We can only do so much with pictures.
 

shardy217

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Jun 21, 2010
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I really appreciate your guys feedback. I may try it after reinforcement. I was going to replace the 6 bolts holding the transom onto the support beams as well. Are these just galvanized bolts? I’ve heard galvanized and aluminum will react but also didn’t think stainless was very structural. Thanks again!!!
 

shardy217

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7DF6BF3E-F3B2-45B6-A86D-B5EB05694DE2.jpeg

Got some good news - finally got ahold of the manufacturer and they sent me a new capacity plate. Looks like my boat is rated for 120HP though I am even unsure about putting a 90HP on it. Just wanted to post this in case someone else has the same problem.
 

HotTommy

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Mar 15, 2013
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Here's some food for thought. First, the boat may have been modified over the years. See if the engine pod looks original. Second, motors don't weigh the same now as they did 30 years ago, and the horsepower ratings may not be calculated the same either. So take that rating placard as guidance but not gospel. Given its age and the corrosive effects of water, you ought to give it a thorough inspection top and bottom just to be safe. .... Good luck with your old boat. I love being out in mine.
 

shardy217

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Jun 21, 2010
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Thanks Tommy. It appears the engine pod is original with no damage to the welds. I want to at minimum replace all the bolts and put some bigger washers on. I was really looking for a 50-60HP but came across a steal on this 89 Suzuki. May end up trading down to that anyway. Guy has some issues with idling and I redid the carbs and she runs like a peach now!
 

NYBo

Admiral
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Oct 23, 2008
Messages
7,107
90 HP is well below the maximum rating for the boat, and being an '89 2-stroke (it is a 2-stroke, right?), its weight should not be a concern. Just make sure to prop it correctly and go boating/
 

shardy217

Seaman Apprentice
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Jun 21, 2010
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48
Yessir it’s a 2-stroke. Hoping to take the boat out within the next couple weeks - will update!
 

shardy217

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Jun 21, 2010
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I forgot to ask - I wanted to replace all the bolts that hold the engine pod to the supports. Someone offered up this info on another post as to what style SS to use but I can’t seem to find it. 4D02F8B0-ACF8-4537-8F6A-4E319A232F11.jpeg
 
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