4 Stroke 15hp Yamaha on my 14' V - hull ---- too much??

TinBoats.net

Help Support TinBoats.net:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

maximajohn

New member
Joined
Mar 30, 2015
Messages
2
Reaction score
0
Hello,

I've been a long time reader and am a new poster to this forum. The maxima forums have been a great help over the years... I appreciate your input:)

Here is my setup: 1400 Spectrum 1989(became bass tracker I think), Fixed Mount Motor Bracket(to lift the motor up 2.5"). I think the Spectrum is rated for 15hp and 700lb capacity(roughly). See quick picture attached.

Here are my questions:

1. I upgraded from a 94' Johnson 15HP(90lbs) 2 stroke to a 15HP(112lb) Yamaha 4 stroke. Is the extra 22lbs too much hanging off 6" from the rear? That yamaha is extremely heavy. I took the boat out and the transom goans and creaks upon acceleration. It did this with the old motor, but not as often or as much. I think I saw the transom flexing some too, but was too attentive to motoring the channels.

2. Should I add diamond plate to the transom to spread out the force?

3. Should I take off the bracket and try to use the Yamaha motor on the transom?

4. Do other people feel the 4 strokes vibrating at idle? My boat has a resonance now and humms as everything inside buzzes. Underway, the engine smooths out and is quiet and awesome. Should I add a rubber or something to help with the vibration?

5. The wood on the transom seems solid, but that is an option to replace.

6. Upgrade the 14' boat to a sea nymph(just throwing it out there) or something stronger? In Tampa Bay there are tons of boats on CL for cheap, so it is an option. I could do a 14' - 15'. I do not care about going super fast. The Sea Nymph looks comparable to my boat, so I just don't know. I just did my trailer axle and hubs, so i want to keep my trailer.


These questions have been building! I will try to post a picture of the transom. Nothing fancy, 1 floor bracket to the transom.

My main concern is taking on water over the transom. To get to the skinny water, i often tango with large boats and their wakes around the boat ramp. That and a transom that is makeing noises does not instill confidence in me.

Thanks,
John
 

Attachments

  • IMG_0547.JPG
    IMG_0547.JPG
    44.3 KB · Views: 517
I am running the same motor on my 1448 flat bottom jon except mine is a 20 hp. My boat is actually rated for a 35 which seems like a bit much to me.

The wood may be rotten, is it just a piece of 3/4 or is it 1 1/2" thick?
 
I'm with CMOS on this, if the transom in question, replace and reinforce it.
.my friend did Aluminum plate on his and some angles.
I just replaced my old worn out wood one.
I run a mercury 4 stroke 15 hp and I'm happy.14' does 24 mph me and a buddy
 
I'm with CMOS on this, if the transom in question, replace and reinforce it.
.my friend did Aluminum plate on his and some angles.
I just replaced my old worn out wood one.
I run a mercury 4 stroke 15 hp and I'm happy.14' does 24 mph me and a buddy

Is the aluminum plate you guys are referring to being used as a transom pad? How is the angle used? I'm just not visualizing what is being done. Thx.
 
Before going thru all this work, you might consider a bigger/ better quality boat. I haved owned a couple 14's over the years, all rated 35 hp or higher, which tells me your boat is a small light duty boat having only a 15 hp rating. If you want to stay with 14' there are wider, deeper, better built boats out there that are 14' long.
 
Nice little boats, but not so good for out in the T. Bay.

That boat is probably not rated for the weight of a 4-stroke. I had a BIG problem recently in a similar boat. Almost lost the boat when the back corner went ker-plunk from the weight of the newer, heavier engine.

I posted about it the other day, I think in this post:
https://www.tinboats.net/threads/2stroke-to-4-stroke-weight.50272/
 
Hello,

I've been a long time reader and am a new poster to this forum. The maxima forums have been a great help over the years... I appreciate your input:)

Here is my setup: 1400 Spectrum 1989(became bass tracker I think), Fixed Mount Motor Bracket(to lift the motor up 2.5"). I think the Spectrum is rated for 15hp and 700lb capacity(roughly). See quick picture attached.

Here are my questions:

1. I upgraded from a 94' Johnson 15HP(90lbs) 2 stroke to a 15HP(112lb) Yamaha 4 stroke. Is the extra 22lbs too much hanging off 6" from the rear? That yamaha is extremely heavy. I took the boat out and the transom goans and creaks upon acceleration. It did this with the old motor, but not as often or as much. I think I saw the transom flexing some too, but was too attentive to motoring the channels.

2. Should I add diamond plate to the transom to spread out the force?

3. Should I take off the bracket and try to use the Yamaha motor on the transom?

4. Do other people feel the 4 strokes vibrating at idle? My boat has a resonance now and humms as everything inside buzzes. Underway, the engine smooths out and is quiet and awesome. Should I add a rubber or something to help with the vibration?

5. The wood on the transom seems solid, but that is an option to replace.

6. Upgrade the 14' boat to a sea nymph(just throwing it out there) or something stronger? In Tampa Bay there are tons of boats on CL for cheap, so it is an option. I could do a 14' - 15'. I do not care about going super fast. The Sea Nymph looks comparable to my boat, so I just don't know. I just did my trailer axle and hubs, so i want to keep my trailer.


These questions have been building! I will try to post a picture of the transom. Nothing fancy, 1 floor bracket to the transom.

My main concern is taking on water over the transom. To get to the skinny water, i often tango with large boats and their wakes around the boat ramp. That and a transom that is makeing noises does not instill confidence in me.

Thanks,
John
You may be able to add 3/4 inch solid plywood to the transom and remove the bracket Be sure to waterproof the plywood and seal the fasteners to prevent water intrusion. I have done this with Jon boats and semi v boats. I have never had a problem with this method. If the boat is wooden a technique to prevent water intrusion is to use a hole saw to create a place for fasteners. Fill holes with fiberglass resin. After fiberglass hardens drill fastener size hole and use sealant on fasteners. There is a product called Coosa board (if memory serves me) that used on transom replacement. It is often utilized on salt water boats.
 

Latest posts

Top