Complete Amateur Needs Help…

[mrbrightside7]

Hi Everyone!

I have been reading through this forum and I am so happy to have found it! There are some real great people here and the advice is fantastic! I just got a small fishing boat with a cathedral hull design. It has an 87 Evinrude outboard on it, 90hp. This is the first boat I’ve ever owned/driven so I want to see if the experience I’m having with it is normal or if there is something wrong with the motor…

The motor starts up great, key start, automatic trim. I trim all the way down and put it in gear to begin moving forward. When in gear at the lowest throttle I move about 1-2 mph. If I start to give it a little throttle the engine revs up, the bow raises and stern dips and I don’t gain much speed, but my wake starts to get a little too much for no wake zones. I am maybe going 3-4 mph at this point. The more throttle I give the engine revs up some, but the bow raises more and the stern drops, almost to the point of water coming in the back, but I gain almost no speed. At about 3/4 full throttle I get to maybe 7-8 mph. If I go full throttle it revs up more, the boat is almost sticking straight up, and I’m going maybe 10 mph. But after about 3-5 seconds it almost seems to jump to another gear. The rpm’s go really high, the boat planes out and all of a sudden I’m going flat out at about 40mph! It’s great, but I hate not having an in between speed. So I have a few questions below that I would love some help with since I’m so clueless as to how this should all work.

1.) Does this seem normal for a boat this size and a motor this size? Honestly, the motor seems a little big for this boat, but I have no idea…
2.) If this is not normal, has anything I’ve explained alluded to any problems with the motor?
3.) If this is normal, one thing I’m wondering is whether or not the prop is the correct size for a boat like this. Will prop size get the boat to drive better at the lower speeds?
4.) Any other advice for me on getting the best performance possible on this boat? Any advice on how I can go at low speeds (5-10 mph) without the hull sticking straight up in the air and needing to be almost full throttle?

Thank you so much for any help!

[garry-in-michigan]

It sounds like you have too much weight in the back of the boat. Move everything you can to the bow (Front of the boat – Facing forward, your port side is on the left and Starboard is on the right.) If that isn’t enough, add after planes to the transom. After planes are flat pieces that act to extend the bottom giving more lift at the rear. . . 🙂

[mrbrightside7]

quote Garry in Tampa:

It sounds like you have too much weight in the back of the boat. Move everything you can to the bow (Front of the boat – Facing forward, your port side is on the left and Starboard is on the right.) If that isn’t enough, add after planes to the transom. After planes are flat pieces that act to extend the bottom giving more lift at the rear. . . 🙂

That’s what I was thinking, sounds like the motor is a little too big (heavy) for this boat. If I have the seats up front and the controls in the middle starboard side of the boat, what else can I move to the front? Just getore people on the boat with me haha?

Also, are after planes a real thing? A quick Google search is coming up with nothing on that? Perhaps they’re called something different?

Thank you!

[PugetSoundBoater]

What is the the max hp listed on the manufacturers tag riveted to the inside of the transom near the motor? How long is this "small fishing boat"? you say it is a cathedral hull, i assume it is fiberglass? If so,has the boat been stored outside where water may have seeped into the core of the foam in between the exterior and interior, adding a lot of weight? Where are you located? Could you post a photo of your boat?
Welcome to the forums!

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson

[PugetSoundBoater]

I see from searching your previous posts it is a fiberglass boat.The reason i inquired as to where you live is if the boat was stored outside in freezing templates , with water inside the hull and or core.

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson

[mrbrightside7]

Than you for the response! The max hp is 90. The boat is about 14′ long. The hull is fiberglass, and there doesn’t appear to be any water in the foam, but I don’t know much about its history, so I suppose that could be a possibility. I am located in Sacramento, CA. Attached is a photo of the boat.

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[frankr]

All boats do what yours does, to a greater or lesser extent. Speed control between making a hole in the water and planing speed just doesn’t exist. What does exist is the great variation in what it takes to get it up on plane, and how slow you can go without sinking back into a hole. After planes are often called trim tabs. Am I seeing a Whale Tail on the motor? Same purpose. If that is what I’m seeing, somebody else was unhappy with the performance too.

I do agree, too much weight in the rear. But don’t have a real answer. The boat might do well with a lighter 50 or 60hp motor, but I’m thinking that probably is not what you want to hear

I’ve seen lots of boats with what others have suggested–water in the hull. Usually when there is an air chamber under the floor. Boats with such an air chamber will have a drain plug to drain the chamber.

Yep, put somebody in that front seat.

[billw]

Some smaller boats with bigger engines on them act as you describe….but the thing is, usually, once you get up on a plane, going fast, you can then back off on the throttle and stay on a plane at somewhat less speed. You should be able to pull it back to 3/4 throttle and stay on plane. Does that happen? If so, I would call it relatively normal.

Long live American manufacturing!

[fleetwin]

Do you know what pitch the propeller is? If it is an OMC prop, the diameter and pitch should be stamped on the side of the prop between the blades. Something like: 13×19…In this example, the diameter of the prop is 13", the pitch is 19". In other words, theoretically the boat should move 19" with every one rotation of the prop. Someone may have over propped the rig with a propeller with too much pitch, which is very common. When this happens, the engine lugs/struggles while trying to accelerate/plane the boat…..The simplest way to relate this information is to think of a manual shift car. What would happen if you had the manual shift car in its highest gear just loafing along at about 25mph, then hit the gas hard to accelerate? Yes, nothing much, other than the engine would probably ping/knock while the RPMs were increasing very slowly. This same thing happens to outboards.

[outbdnut2]

quote mrbrightside7:

That’s what I was thinking, sounds like the motor is a little too big (heavy) for this boat. If I have the seats up front and the controls in the middle starboard side of the boat, what else can I move to the front? Just get more people on the boat with me haha?

Move the gas tank to the front (you can buy or make a longer gas line), and if you buy extra wire, you can move the battery up front too. If you carry an anchor, store it up front.
Dave

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