Problem getting bow to drop

[Phacerros]

I recently purchased a used boat (first boat) and my father and I took it out on the lake. If we sit in the seats and take off, the boat will raise to about 40 or 45 degree and wants to stay there. It would move about 10 to 15mph at best. The water behind the boat would come up against the bottom of the motor. We took the boat in to have it checked out. A guy suggested a different prop. The #23 (i think it was) was pulled off and a #17 was put on. We took the boat back out and the bow would drop, but you would think the boat was going to go under before it would do so. We left the boat for a few days and picked it up again. We were told it should be fixed. On the boat now is an unnamed prop with no number that I can see. It is a prop with larger blades than the origional that was on it, that I am fairly sure of. He didn't charge for working on it or for this different prop, so I guess that is a good thing.

Now, from the first time we took it out to it's current state, if someone will get all the way up into the bow the boat will take off perfectly, the bow stays down and it will fly across the water. As it currently sits, to get the bow to stay down you need to be just above idle or almost wide open.

We tested this with just 1 person weighing about 230lbs in the boat and it does the same thing.

The boat is about 17ft with a 90hp engine that was just bored out and rebuilt and is now a 115hp.

Thanks for any advice on how to remedy this.

First post by the way.

 

[RangerRob]

Welcome Phacerros. Not to trivialize your post, but I gotta ask because you failed to mention it ... how are you trimming your motor? Could you give us some details on where your motor is trimmed at take off and where it's trimmed on plane? This is huge and will help greatly since it could be a rookie mistake and not the prop. Every boat/motor combo has a different sweet spot for the trim range and you just may not be hitting it once the boat has come out of the hole...

 

[dtw2]

motor needs to be trimmed all the way down when taking off, this will help coming out of the hole, other things to look at is prop pitch and the rpms you are turning while running. One other thing is also learning the boat, ever boat is different when it comes to driving. you just need to find the sweet spot in come out and also staying on plane, you may need a whaletale, if so I have one if interested. this will help.

 

[crawdad048]

whaletail made a BIG difference on my boat.

 

[kickinbass35]

i had the same problem with the same size boat and engine that you have a whales tail fixed it rite up also i had the same type prop no name no nothin on it it was a michigan hub brand the name and pitch of the prop was on the inside behind the thrust washer

 

[Liveliner]

Trim all the way in - Check to see that you are not restricted. The engine will be on a angle steeper than your transome at full trim in. When the RPMs rise a little and the nose settles down start trimming the engine out slowly untill you reach your max Rpm or untill you reach the point where you get a balanced feel in the steering. But never more than your maximum RPMs.

Engine power and/or prop with too much pitch - You should hear your engine strain at the first few seconds then you should hear the RPMs start to increase on a sharp curve as you gain speed. If your RPMs are not increasing fast enough, Change props.

Whale tail - Those planer tabs would help you but due to the extreme you are experiancing, it would not solve your problem.

Depth of the foot below the hull - Did you change engines on that boat? If so, was the foot on the new engine longer than the engine taken off? You may be getting too much drag fron an engine way too deep below your transome. For example if you removed a 20" foot and installed a 25" foot.

 

[Phacerros]

Whale Tail seems to have cured it. Major difference in it now.


Thanks for the tips.

 

[dtw2]

Glad to see the tail help, but i would still have rpm guage fixed and check position of motor on transom, it my be too low.emoThumbsup emoToast

 

[digitalcb]

dtw2's advice could save you a lot in fuel economy. You need to know how your engine is running and if you have unnecessary drag.