Sx230 ho top speed?

[Krzysiek]

I took the boat for test run before I purchased it last November. Top speed was 47mph. Then I installed Thrust Vectors xl and top speed was 44mph.

Do they create drag and boat slows down? It is only 3mph difference.

I do not care much about top speed. I just want to know if it is because thrust vectors or possible boat or engine problems?

 

[Speedling]

You didn't drop that much from tv's.
Perhaps something is out adjustment from the install?

 

[bronze_10]

That by the speed o or the gps?

 

[Krzysiek]

by the boat speedometer, not the GPS

 

[bronze_10]

I always check through my phone and use the gps... who know what kind of trash or weird water flow may affect the speed o

 

[OperationROL]

First, it is not the TV's. When was the last time you did a spark plug change. This is consistent with a fouled spark plug. Do you notice an RPM drop? Also, what is the condition of the impellers? Are you using old fuel?

 

[Krzysiek]

I took the boat for the test when I purchased it and one time 4 weeks ago for the first time. The yamaha dealer changed spark plugs, oil and winterized it in November last year. Old fuel with stabilizer from last year. Impellers condition did not change in 2 uses, I think.

 

[bronze_10]

I put tv on my boat and did not notice any change in speed... but I always do it with gps... gps will say 48 and the boat will say 51..

 

[Bill D]

Like @OperationROL said, I'd start with changing the spark plugs. It is possible that the dealer fogged the engines and fouled the plugs.

 

[OperationROL]

I took the boat for the test when I purchased it and one time 4 weeks ago for the first time. The yamaha dealer changed spark plugs, oil and winterized it in November last year. Old fuel with stabilizer from last year. Impellers condition did not change in 2 uses, I think.

OK. Try putting some SeaFoam in the tank and top it off with fresh fuel as a first test. Eventhough the fuel had stabilizer it still breaks down as well as water can and probably will build up in the tank due to condensation during storage. Then go to the spark plugs. I have seen it a million times.

 

[Krzysiek]

Thanks.
Is it better to change spar plugs and oil at the end of season or beginning of a new season?

 

[OperationROL]

Thanks.
Is it better to change spar plugs and oil at the end of season or beginning of a new season?

This has been debated over the years. There are many good reasons for either, but I, myself, prefer changing oil and spark plugs in the Spring, especially if you fog the engines during winterization and introduce a chance to foul the plugs.

 

[Rod5]

How about the difference in fuel loads?
Perhaps in the fall you had a half tank or less, then you topped it off for the winter storage, so perhaps your recent run was with a full fuel load... Just think'n out loud.

 

[swatski]

There are so many things that affect top speed. It is NOT the TVs.

 

[Gym]

@Krzysiek. It may have been a more accurate test to do a test run on the same day before installing the TV's, then another test run just after the install as wind, water, bimini position and boat loading conditions all could have been different enough to have caused this difference. I would consider replacing your spark plugs as was previously mentioned. Keep 4 of the old plugs as spares in your glove box incase you need them while on the water. Also look at the TV's from the rear of your trailered boat. Make sure they are vertically parallel. If your nozzles are slightly out of alignment the TV's will amplify this problem by creating drag.

Most mechanics I know will tell you to change the oil in the fall so the engine is not being bathed in acid laden oil all winter. Change the spark plugs in the spring AFTER the initial start up to burn off the fogging oil. With regard to the oil, we can only remove about half of the oil so there is not a big issue when you change it.

 

[Bruce]

by the boat speedometer, not the GPS

The boats speedometer is useless. Get a GPS based top speed before you get concerned about it.

 

[Dieselpwr]

was this tested on the same water under the same conditions?

 

[Krzysiek]

was this tested on the same water under the same conditions?

first test:
air temp: about 50F, no strong wind, salt water, Shinnecock Bay, Long Island, NY (smaller bay), flat water condition

second test:
air temp: about 70F, no strong wind, salt water, Long Island Sound outside Mt. Sinai, NY , flat water condition

Water condition was the same during both tests.

 

[Bruce]

The boat speedometer does not provide consistent readings. It is not useful for comparison.

 

[Paulie]

I changed over to TV's and have not noticed any drop in top speed. (GPS)