Advise on prop selection Searay 270DA 1996 2x3.0lx

[Skutnik Robert]

Hello,
Can somebody advise me which props should I put on the boat. Curently instaled is 14" x 19P Vengance. But needs a lot of time to start gaining speed- almost no accelaration. End speed fully loaded is 24mph it should be greater. Load capacity 2 adults (170kg )+ 2 child ( 30kg boath), watter 150l, 350l petrol, abd bits and pices 200kg.

Thank you in advance.
SeaRay 270 DA 1996
Mercruiser Twin 3.0lx 135hp

Regards
Robi

 

[Lazy Daze]

Twin 4 cylinders? Are you sure? I think the twin option was V6's. BUT, if that's what you have, that's what you have - maybe somebody replaced the V6's at some point. I see you mentioned "petrol"... so you're outside the US? Maybe there were different options available outside the US.

OK, so... that's a lot of boat to push with 4 cylinders. I'm not surprised it's taking a while to get up on to plane. But your top end speed should eventually creep up. Answer the following questions to help steer help in the right direction

-- Are you measuring speed with the boat speedo or GPS? Must be using GPS for our purposes.
-- What's your final RPM when going all out?
-- When going all out (WOT), are you trimming up as much as possible?
-- When going all out (WOT), are you fully retracting the tabs?
-- Are you trimming both engines FULLY down on take off?
-- Are you using trim tabs fully deployed on take off?
-- Is the boat bottom PERFECTLY clean?
-- Are the props is good shape?

 

[Skutnik Robert]

Twin 4 cylinders? Are you sure? I think the twin option was V6's. BUT, if that's what you have, that's what you have - maybe somebody replaced the V6's at some point. I see you mentioned "petrol"... so you're outside the US? Maybe there were different options available outside the US.

OK, so... that's a lot of boat to push with 4 cylinders. I'm not surprised it's taking a while to get up on to plane. But your top end speed should eventually creep up. Answer the following questions to help steer help in the right direction

-- Are you measuring speed with the boat speedo or GPS? Must be using GPS for our purposes.
-- What's your final RPM when going all out?
-- When going all out (WOT), are you trimming up as much as possible?
-- When going all out (WOT), are you fully retracting the tabs?
-- Are you trimming both engines FULLY down on take off?
-- Are you using trim tabs fully deployed on take off?
-- Is the boat bottom PERFECTLY clean?
-- Are the props is good shape?

Hi,
1. Using Gps speed
2. 3458RPM
3. max trim
4. fully retracted tabs
5. Boat botom perfect shape
6. props cleaned and refurbished

The boat does creep up but slowely only in perfect weather condition. This week test. Thank you for any advise. Will take it to my knowledge.

Regards
Robi

 

[Lazy Daze]

Robi, you're missing some of the answers. Please click the "reply" button in the bottom corner of my post and respond to each question directly.

Other than that, with what you've written so far, I do not think the prop is the issue. The fact that you can't get higher RPM's doesn't correlate with ALSO a slow hole shot. Hopefully the issue is just "user error" - because another explanation is/are bad engines. But I'd also verify that your throttle is opening all the way on both carbs.

Do a compression check. With 4 cylinders, this will be a piece of cake as far as access goes.

 

[Scott215]

Four-cylinder should still run at least another thousand RPMs

 

[techmitch]

Hi,
1. Using Gps speed
2. 3458RPM
3. max trim
4. fully retracted tabs
5. Boat botom perfect shape
6. props cleaned and refurbished

The boat does creep up but slowely only in perfect weather condition. This week test. Thank you for any advise. Will take it to my knowledge.

Regards
Robi

Are you sure you have a 1996 270 DA. Can you post the hull ID.#

They don't list that engine/drive combo in the spec. sheet,
https://owners-resources.searayweb.com/model-archive-files/1C1_27_74DERNS6K861.pdf

or the prop matrix.
https://owners-resources.searayweb..../1996 Sport Boat Sport Cruiser Prop Chart.pdf

If you actually have those engines in a 1996 or 1997 my bet is that you probably have drive gear ratio and prop spec. issues, even if the engines are running perfectly.

 

[Skutnik Robert]

Are you sure you have a 1996 270 DA. Can you post the hull ID.#

They don't list that engine/drive combo in the spec. sheet,
https://owners-resources.searayweb.com/model-archive-files/1C1_27_74DERNS6K861.pdf

or the prop matrix.
https://owners-resources.searayweb.com/propeller-charts-files/1996 Sport Boat Sport Cruiser Prop Chart.pdf

If you actually have those engines in a 1996 or 1997 my bet is that you probably have drive gear ratio and prop spec. issues, even if the engines are running perfectly.

Its the 1995 built year. I have checked.

 

[Skutnik Robert]

Four-cylinder should still run at least another thousand RPMs

I think so up to 4800 RPM should be WOT

 

[techmitch]

Hello,
Can somebody advise me which props should I put on the boat. Curently instaled is 14" x 19P Vengance. But needs a lot of time to start gaining speed- almost no accelaration. End speed fully loaded is 24mph it should be greater. Load capacity 2 adults (170kg )+ 2 child ( 30kg boath), watter 150l, 350l petrol, abd bits and pices 200kg.

Thank you in advance.
SeaRay 270 DA 1996
Mercruiser Twin 3.0lx 135hp

Regards
Robi

Your first post says it's a 96, your user info. says you have a 97, now you tell us it's a 1995.
Sure would like to help.

 

[Skutnik Robert]

Your first post says it's a 96, your user info. says you have a 97, now you tell us it's a 1995.
Sure would like to help.

Sorry for all the wrong data. The boat was bought in Croatia with wrong build year in papers. But I have found the year built trogh HIN just this week. Sorry for missleading.

regrds
Robi

 

[Skutnik Robert]

I have also found as I'am rebuilding the carbureators that one is MerCab 43 mm and MerCab 36 mm. Now trying to find which one is correct so I match boath carbureators.

Im first time owner of the boat. Found a lot of problems this season and trying to remove them trough winter.

Regards
Robi