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What prop on 2007 BF75D?

Ruigie

Member
Last year I bought a 2010 Beneteau Antares 580 with a BF75D 2007 mounted.
Untill now I mainl6 used it at low speeds for trolling but last week I took it for a 15 mile trip to the drydock to revise the engine.
It only picked up speed when I surfed some waves , otherwise it kept speed at about 13 knots.
The mecanic (not a Honda mecanic) said it could be the prop, which was new when I bought the boat.
What prop is recommended for a 2000 lb vessel ?
don’t need speed, the seas around here in the Biscay bay area normally don’t allow so.
inside the bay it gets up to speed,around 25 knots,but otherwise it doesn’t get in to plane easily.
thanks
 
Let's start with some more info. What max rpm are you achieving with your current prop and at a size is your current prop?
 
Let's start with some more info. What max rpm are you achieving with your current prop and at a size is your current prop?
The actual prop is a 10 17.
don’t know the exact revs as my meter is malfunctioning , when it was working inside the bay wot it would go to abt 5500.
At sea with 1-1,5 mts waves it didn’t get into plane unless riding a wave.
 
If we had the correct size for your existing prop, we might be able to come up with an educated guess (based on experience) for a prop that might do a better job. What may make that guess even more educated would be to know the rpm that prop is turning at wide open throttle.
 
If we had the correct size for your existing prop, we might be able to come up with an educated guess (based on experience) for a prop that might do a better job. What may make that guess even more educated would be to know the rpm that prop is turning at wide open throttle.
Prop mounted now is a 13.25 x 17 so should be correct.
made the trip from yard to berth today with 1 + meter waves and at full throttle rpms around 3500 speed around 10 knots.
inside the bay it does get into plane and picks up speed upto 25 knots with abt 5500 rpm.
used to have a similar boat with a 2000 Yamaha 80 which would get into plane in any condition or load.
your educated guesses very much appreciated.
 
I'm not sure going with a smaller prop is the answer here. The issue would be the rpm's the engine would be turning with that smaller prop when on plane!

This sounds more like a case where your boat is WAY under powered. Maybe the motor size selected based with a priority on cruising only? A 4 blade 15" prop may help as a last resort, but it may require attention regarding rpm's in calm water at wide open throttle.
 
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I'm not sure going with a smaller prop is the answer here. The issue would be the rpm's the engine would be turning with that smaller prop when on plane!

This sounds more like a case where your boat is WAY under powered. Maybe the motor size selected based with a priority on cruising only? A 4 blade 15" prop may help as a last resort, but it may require attention regarding rpm's in calm water at wide open throttle.
Have the feeling that indeed it is underpowered, although not sure if so much as WAY because most of these boats normally have 90 hp engines which is not really a big leap.
max hp for this boat is 100 hp.
To do a “cheap” test I ordered a SE 400 hydrofoil to see if this could be a solution as some say.
No drilling requiered so if it doesn’t work I take it off and sill reconsider selling this engine and go for a BF 100...
thanks againfor your advise!
 
One more question, is this boat dry stored or kept in the water? Just for the record, there is not a lot of difference between a 75 and 100, I had a customer upgrade from a 75 to 100 , same boat, same prop, he gained 3 knots and 300rpm, strange but true. Perhaps you should be looking at things like water in the hull, growth etc.I still maintain that having looked at your boat specs, it should perform well with a BF75 carrying a light load

.
 
One more question, is this boat dry stored or kept in the water? Just for the record, there is not a lot of difference between a 75 and 100, I had a customer upgrade from a 75 to 100 , same boat, same prop, he gained 3 knots and 300rpm, strange but true. Perhaps you should be looking at things like water in the hull, growth etc.I still maintain that having looked at your boat specs, it should perform well with a BF75 carrying a light load

.
I did the hull last week when it was on the docks, normally it’s afloat at the birth but not to much growth on it.
I agree with you that this boat should perform much better with this engine and sometimes it seems to me that the boat is lying heavy in the water.
However I don’t see any water in the hull and beside the fishing stuff and the two anchors there is not much weight on board.
I will try leaving most of the heaviest stuff on the shore but it shouldn’t make that much difference.
Top speed isn’t the priority but with average sees it should perform better,planing at 15 knots is my aim.
 
Let's start with some more info. What max rpm are you achieving with your current prop and at a size is your current prop?
Just tested again, this time rev gauge seemed pretty accurate.
at WOT on flat water achieved 24 knots at 4800 revs, didn’t go higher.
then alarm went off , engine finally stalled and after a minute started without any alarm.
 
So there's another issue in play here. One that needs some attention ASAP.

How old is the water pump impeller?

When the alarm went off did you have a red light on as well?
 
So there's another issue in play here. One that needs some attention ASAP.

How old is the water pump impeller?

When the alarm went off did you have a red light on as well?
Impeller changed last week (old one had less than one year and was in good condition)as well as internal anodes, all oils and filters, sparkplugs checked and calibrated .
yes red light came on.
 
Most common cause of overheat on the BF75D is salt build up around the block thermostat behind the electrical component case.
 
Most common cause of overheat on the BF75D is salt build up around the block thermostat behind the electrical component case.
Changed that thermostat also and cleaned housing all the way inside .checked after a run and it was obvious stat opened up and water ran through it.
also checked temp with heatgun and marked around 149 F
 
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