Real World Speed for Trophy 1703 with Mercury 90 HP

[tuggator]

Hello,

I have searched the forums and there are several other Trophy 17 with 90 HP Mercury outboatd owners that have posts on the forums. My question for fellow Trophy 17 owners is: What is your real world Speed experienced.

I am interested because since I bought this boat last summer and only used it a about a dozen times the speed is not very impressive. I had a similar boat as a kid a 17' Whaler Montauk with a 90 HP Evinrude and that boat was topping out at almost 40 kts SOG. My Trophy will wind out at about 20 kts in the most favorable conditions. My Trophy has a new stock prop and aftermarket hydrofoil on the lower unitI added early last season to help it get up on plane.

Anyway I hope I can get some input from the forums to see if there is something I can do to increase performance without replacing the engine.

Thanks Tug Gator

 

[JoLin]

Re: Real World Speed for Trophy 1703 with Mercury 90 HP

Hi, Tug.

20 kt/23 mph sounds much too slow. But give us some basics. Are you measuring SOG via GPS, or something else? Is your motor reaching Merc's recommended RPM at WOT (wide open throttle)? You need to look it up if you don't know. WOT revs either over or under what Merc calls for would indicate that A) your prop has either too much or too little pitch, or B) if it isn't reaching full RPM the motor might not be running correctly.

 

[Bob_VT]

Re: Real World Speed for Trophy 1703 with Mercury 90 HP

Welcome to iboats

Since it was "new" to you we need to check a few things out to determine why it is going slow.

Do you have a Tachometer hooked up with the Mercury? What is the WOT (wide open throttle) RPMs while on proper plane? Depending on the model (it would be best to let us know) the RPMs should be around 5500 at WOT.

How old is the boat? Have you had it weighed to make sure you are not hauling an extra 500 lbs of wet foam?

Examine your stock prop and post the pitch and diameter. Stock is a very generic term.

I suspect you might have a motor issue and are not attaining WOT.

Let us know...... it will be fixed and you should have about 35-38 mph out of it.

 

[greenbush future]

Re: Real World Speed for Trophy 1703 with Mercury 90 HP

I have the same 90 merc on a 19 aluminum, 30-34 MPH is about all I can manage. There are only a handful of reasons, prop, engine, boat/weight, but with more data, it will help ya get it dialed in right. How old is your trophy? weight? Pictures of your rig always helps too.
Could be any one of the above, or a combo of a couple of them. The add on foil is sometimes a sign that the engine is struggling, depending on how big your boat is, how old, maybe the water in the foam is killing performance. These are all just guesses, but the 90 usually should perform better than what you're claiming.

 

[dingbat]

Re: Real World Speed for Trophy 1703 with Mercury 90 HP

According to boatest you should get 36 mph out of that combo

 

[tuggator]

Re: Real World Speed for Trophy 1703 with Mercury 90 HP

Thanks everyone for your thoughts and input.

Neither my tach or fuel gauge work so once I get that looked at I will try and get the performance issues addressed. I found bottom in a lake last summer and replaced the original prop with a brand new version of what was onboard. Also since the boats fuel gauge doesn't work and it has a 38 gallon tank I usually keep it is topped off. A full tank equates to about 2 full grown adults onboard. Either way I am sure this craft was meant to go faster than 20 it's SOG.

 

[tuggator]

Re: Real World Speed for Trophy 1703 with Mercury 90 HP

I have the same 90 merc on a 19 aluminum, 30-34 MPH is about all I can manage. There are only a handful of reasons, prop, engine, boat/weight, but with more data, it will help ya get it dialed in right. How old is your trophy? weight? Pictures of your rig always helps too.
Could be any one of the above, or a combo of a couple of them. The add on foil is sometimes a sign that the engine is struggling, depending on how big your boat is, how old, maybe the water in the foam is killing performance. These are all just guesses, but the 90 usually should perform better than what you're claiming.

Thanks for your response. I am traveling but will get pics of the boat up online when I can.
Tug Gator

 

[tuggator]

Re: Real World Speed for Trophy 1703 with Mercury 90 HP

According to boatest you should get 36 mph out of that combo

Dingbat

Thanks for the heads up on hat once I get the tach sorted I will double check my prop. Also will replace spark plugs before launching. Hopefully it will be an inexpensive fix.

Tug Gator

 

[tuggator]

Re: Real World Speed for Trophy 1703 with Mercury 90 HP

Welcome to iboats

Since it was "new" to you we need to check a few things out to determine why it is going slow.

Do you have a Tachometer hooked up with the Mercury? What is the WOT (wide open throttle) RPMs while on proper plane? Depending on the model (it would be best to let us know) the RPMs should be around 5500 at WOT.

How old is the boat? Have you had it weighed to make sure you are not hauling an extra 500 lbs of wet foam?

Examine your stock prop and post the pitch and diameter. Stock is a very generic term.

I suspect you might have a motor issue and are not attaining WOT.

Let us know...... it will be fixed and you should have about 35-38 mph out of it.

Bob

I believe I replaced the prop with a either quicksilver xyz 19, or xyz 21 prop....I will have to do more research than that. Where would I weigh my boat? Bring it to the transfer station? The boat I believe is dry because its trailer stored and there is no delamination on the boat. I am think the significant weight factor is the fact that the fuel gauge is out of commission and I keep the 38
gallon tank topped off. I am going to have the tach issue addressed, replace the spark plugs and clean the battery terminals. If there is no noticed improvement in performance, I will bring it into the shop and have them check compression and see if All 3 cylinders are working.

 

[MikDee]

Re: Real World Speed for Trophy 1703 with Mercury 90 HP

No wonder your top speed is so slow with 38gals of fuel onboard, right off the bat!

 

[saumon]

Re: Real World Speed for Trophy 1703 with Mercury 90 HP

No wonder your top speed is so slow with 38gals of fuel onboard, right off the bat!

The boat in my signature (similar in size and hull shape to the OP one) regulary do 38mph (sometines 40mph on glass-like conditions) with a 90hp, a kicker, a trolling motor, 2 batteries and a full 34 gal. tank, but my engine is on the highest setup on a manuel jackplate and I run a 17p SS prop.

At 23mph, there's definately something wrong, you should easily reach at least over 30mph (Boattest.com report a top speed of 36mph with the same setup http://www.boattest.com/boats/boat_video.aspx?ID=540). First thing to do is to get a working tach (in-dash or a TinyTach) and make sure you reach the engine recommended rpm at WOT. I highly suspect that you're lugging that engine (too heavy boat / too much pitch prop)...