Should my boat be faster than it is?

[Todd in NY]

I have a 19ft aluminum Sea Nymph deep V center console with a 1986 90hp Evinrude. The boat dry weight with 2 motors, including my 15hp Evinrude, is roughly 1450 lbs. The prop is 13.25x17 and is a 3 blade aluminum. The boat doesn't have a tach, so I don't know what RPM its running at WOT, but it hits 32 MPH on the GPS with 4 adults that weigh a combined 900 pounds, plus all fishing gear (2 electric downriggers, etc), a full tank of water in the livewell and 6 gallons of gas left in the 24 gallon tank. It planes out real nice at WOT. I feel a little vibration from the prop while accelerating at lower RPM's, but it quickly goes away as she picks up speed and starts to plane out. Is 32 MPH all I should expect or can I find another 5 MPH with a different prop? I don't tow tubes or skiers, it's strictly a fishing boat for Lake Ontario and local inland lakes and rivers.

I've heard from other boaters with a similar boat and the same motor size getting 38 MPH, but maybe they were riding solo without gear. Just curious...

 

[dwco5051]

Your speed seems to be in the ballpark. I have been running powerboats for 65 years now and I can count on one hand how many people I know who I will believe when they tell me how fast their boats are.

 

[muskyfins]

Well, you can believe me.....:laugh:

I have a 16 foot smokercraft magnum dual console with a 1986 75 mariner. IIRC-same prop as you. I get 38 MPH as measured by 2 different handheld GPS units but........

that is on smooth water with no wind, trimmed all the way up right before prop blows out
no wind=no wave action
I have 3 less feet of aluminum in the water than you/probably 20% less drag
that is with only me in the boat (although I'm a big guy, I'm 550 pounds less than your payload)
a 15 gallon livewell holds another 112 pounds of water
if you've got 4 people in the boat, you've probably got more weight in fishing gear than me
Down riggers, at least 15 pounds each
Kicker motor has to be another 100 pounds (maybe more)

I wouldn't be too unhappy with 32 MPH. Have you run a trial without the extra payload? Smooth water?

 

[steelespike]

If we safe going to do this right we need a tach.If we calculate to "best guess" rpm 17", 2.00 gear ratio,32 mph with 12% slip we get 5000 rpm.Guessing rpm is not the best away to evaluate your setup.An induction tach will work.
Is the speed free of any current or wind?
86 developes hp at 5000 probably at least 5500 wot rpm.
I feel that we can get a better feel for the setup with all the extra weight removed.
If truly a deep V that may slow things a little.

 

[64osby]

1973 21' Starcraft Mariner with 4 on board (600lbs) 7.5 kicker and a 1985 90 Rude, gets to 38mph all day long.

Solo I've hit 41 in perfect conditions, wind behind me, going down hill.

 

[Todd in NY]

Thanks for the quick feedback fellas! I haven't had a chance to run solo as a comparison yet. The prop is in perfect condition, the boat is deep, 33" gunwale height. My last run when fully loaded was in a light wind of 5 MPH, very light chop, and no current. I had the bimini rolled up in the zippered cover. I forgot to mention that I had my 70 lb thrust trolling motor and 2 size 24DC batteries for it up front, so there's another 120 pounds of gear. I guess 32 MPH is pretty good considering the load it was carrying. Also, I didn't have enough of a straight-away to tweak the trim position, so it was trimmed all the way down. I will experiment with different trim settings my next time out as well. I'll leave the electric trolling motor and the 2 batteries at home as well. And there will only be 3 adults next time out.

I know the boat sat for 2 years before I bought it, so I will do a full service on the motor, carbs, lower unit and everything else that needs to be done. I'm sure the motor performance might be holding me back a little. I ran some fuel system cleaner through it to help out, and some K-100 fuel treatment because there was some moisture on the under side of the fuel cap 2 fishing trips ago (Labor Day). The spark plugs are the right color but I'm sure the carbs need some TLC. I think it will run a little better and faster next year after I do some thorough engine and fuel system maintenance on it this winter and next spring.

 

[Todd in NY]

If we safe going to do this right we need a tach.If we calculate to "best guess" rpm 17", 2.00 gear ratio,32 mph with 12% slip we get 5000 rpm.Guessing rpm is not the best away to evaluate your setup.An induction tach will work.
Is the speed free of any current or wind?
86 developes hp at 5000 probably at least 5500 wot rpm.
I feel that we can get a better feel for the setup with all the extra weight removed.
If truly a deep V that may slow things a little.

What kind of tach would you recommend? I have a handheld one for diagnostic purposes that attaches to a spark plug wire, but I wouldn't feel comfortable running at WOT with the cover off the motor on the open water.

 

[Todd in NY]

This is a pic of my boat, 89" beam

 

[Chris1956]

Gee, I would think 35+MPH would be easily achievable with that power.

 

[Scott Danforth]

I have a 19ft aluminum Sea Nymph deep V center console with a 1986 90hp Evinrude. The boat dry weight with 2 motors, including my 15hp Evinrude, is roughly 1450 lbs. The prop is 13.25x17 and is a 3 blade aluminum. The boat doesn't have a tach, so I don't know what RPM its running at WOT, but it hits 32 MPH on the GPS with 4 adults that weigh a combined 900 pounds, plus all fishing gear (2 electric downriggers, etc), a full tank of water in the livewell and 6 gallons of gas left in the 24 gallon tank. It planes out real nice at WOT. I feel a little vibration from the prop while accelerating at lower RPM's, but it quickly goes away as she picks up speed and starts to plane out. Is 32 MPH all I should expect or can I find another 5 MPH with a different prop? I don't tow tubes or skiers, it's strictly a fishing boat for Lake Ontario and local inland lakes and rivers.

I've heard from other boaters with a similar boat and the same motor size getting 38 MPH, but maybe they were riding solo without gear. Just curious...

so your boat only does 32. your motor is pushing 1450# of boat, 900# of people, about 300# of water in the livewell, and 250# of fishing gear. What is the capacity rating of your boat?

My guess is you have a lower pitched prop since it comes out of the hole easy.

how fast does your boat go with only one person on board, no water in the livewell and half the gear left on the dock?

adjusting the prop will be easy once you get the RPM numbers

 

[steelespike]

Your tach should work.With a little common sense of water conditions and hazards in the boat.
Dragging the bimini through the air will surely slow things especially even a light wind.

 

[Todd in NY]

Boat weight capacity is 1850 lbs for motor, gear and people. Looks like I have it maxed out, so 32 MPH doesn't sound so bad when you put it that way. The bimini was rolled up like it is in the picture above, and I know it creates some drag. I've never had it out on a solo run with no gear yet. I have one more day to run the boat this year, and that is 10 days from now. I probably won't have time to do more testing with it until next year. I'll be focused on fishing one last time for the year with my family. Winter is right around the corner for us and I have more than enough chores to complete before the snow falls. I don't have any other boat to compare it to, but I just want to make sure I am getting max performance out of my boat. I'm very happy with it, and wouldn't trade it for anything. Thanks for all the feedback. I'm learning a lot on this forum.

 

[Scott Danforth]

that was kind of my thought. I bet with a prop change and half the stuff in it, you could easily hit upper 30's

 

[Todd in NY]

I agree with the possibility of higher speed with minimum weight, Scott. Thanks for helping me see the big picture here.

 

[b.gagnon]

I have a 17' Sea Nymph cc with a 90hp merc running a 19p stainless prop turning 5300-5400rpm......
3guys gear 24 gallons of gas = 36mph gps on a good day!
I would say that you are doing well!
It is not a fast hull...but has a good ride for what it is.

 

[Todd in NY]

Thanks for the feedback. I agree that the hull provides a fantastic ride. I don't see myself ever selling it for a "better" boat. It gives me all the versatility I could ever ask of a boat, from rivers to small lakes to Lake Ontario, from panfish to bass to walley to trout and salmon, it truly is a boat for all types of fishing.

 

[b.gagnon]

They are great boats....unfortunately mine is sitting and rotting! I bought a fiberglass center console a few years ago and never tried to sell the Sea Nymph!
It was a very wet ride but could take a pounding( only used it in the ocean). I would suggest one upgrade that made a big difference for me and that is TRIM TABS...... I put lencos on. It would stay on plane @ 16mph! and I could trim the hell out of it when running fast.

 

[Frank Acampora]

Just remember: Everyone's boat is slower than it should be---until they go to sell it, then it is always faster than it should be.

 

[Todd in NY]

I never considered trim tabs, so I will do my research this winter. My cc191 can be a wet ride, but only in real windy chop, and if I am hitting the waves sideways against the wind. It handles 4 foot waves extremely well on Lake Ontario.

Frank, I've seen that all too often