Prop blow out, needing help

J

jbeener1

Petty Officer 2nd Class
Joined
May 17, 2013
Messages
122
Re: Prop blow out, needing help

If the prop does not have cupping and cupping is added does this change the pitch of the prop?
 
Scott Danforth

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
48,093
Re: Prop blow out, needing help

take a pic from the side of the boat with your motor in the normal running position.

make sure your far enough back that we can see the keel line as well as the anti-cav plate.

also take a shot from the back of the boat directly at the propeller, making sure the entire transom is in the picture.

something doesnt sound right with the setup. we should see something from the pictures
 
J

jbeener1

Petty Officer 2nd Class
Joined
May 17, 2013
Messages
122
Re: Prop blow out, needing help

Scott Danforth said:
take a pic from the side of the boat with your motor in the normal running position.

make sure your far enough back that we can see the keel line as well as the anti-cav plate.

also take a shot from the back of the boat directly at the propeller, making sure the entire transom is in the picture.

something doesnt sound right with the setup. we should see something from the pictures
Click to expand...

Lord willing i will take pics on Monday. Thanks
 
S

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Prop blow out, needing help

jbeener1 said:
If the prop does not have cupping and cupping is added does this change the pitch of the prop?
Click to expand...
Cupping can change the effective pitch of the prop.Sometimes calculators suggest to add 1" in pitch for a cupped prop.
 
S

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Prop blow out, needing help

You may be able to have a prop shop add some cup.
If its a solas prop it may already have some cup.
Just be sure the shop is well acquainted with prop alteration.
I would try some of the other suggestions first.
 
Sea Rider

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Re: Prop blow out, needing help

Before investing blindless on a new prop or even modifying current one, you must test best engine/transom height match on flat calm, no wind waters. Having dialed sweet best height, combo will work well on almost all water conditions. Once you have finishes this height test, install an induction tach, go for a wot spin with you alone and light loaded boat and check max achieved rpm, compare numbers to wot factory stated engine parameters to know if over or under propped. Then can play with +,- 4 blades pitches and pick the one that will give near or top wot rpm for that engine.

Happy Boating
 
D

dazk14

Ensign
Joined
Jul 22, 2008
Messages
966
Re: Prop blow out, needing help

Let's see the pictures. Including close ups of the front face of trailing edge of the prop.

Any shop that repairs props, can quickly add a little more cupping. It is very easy to do.

I agree, let's get a closer look before that.

Since it sounds like a garden variety Aluminum boat ventilation and unless you are already lugging that motor I wouldn't Futz with it to long before adding some cup, it's nearly always a good performance Mod.

Do you have a local prop shop? On a smaller prop, they may be able to do it for ~$30. But, unless your a shop, turnaround can be lengthy during the busy season.
 
J

jbeener1

Petty Officer 2nd Class
Joined
May 17, 2013
Messages
122
Re: Prop blow out, needing help

dazk14 said:
Let's see the pictures. Including close ups of the front face of trailing edge of the prop.

Any shop that repairs props, can quickly add a little more cupping. It is very easy to do.

I agree, let's get a closer look before that.

Since it sounds like a garden variety Aluminum boat ventilation and unless you are already lugging that motor I wouldn't Futz with it to long before adding some cup, it's nearly always a good performance Mod.

Do you have a local prop shop? On a smaller prop, they may be able to do it for ~$30. But, unless your a shop, turnaround can be lengthy during the busy season.
Click to expand...
I do have a local prop shop thats been in business for many years. Here are some pictures,hope they help.001.jpg002.jpg003.jpg004.jpg005.jpg
 
F

Fed

Commander
Joined
Apr 1, 2010
Messages
2,457
Re: Prop blow out, needing help

In the 2nd picture it looks lie it has a big hook in the hull.
 
J

jbeener1

Petty Officer 2nd Class
Joined
May 17, 2013
Messages
122
Re: Prop blow out, needing help

Fed said:
Let me google that for you

Pictures can be deceiving so it might be worth running a string line or straight edge along it.
Click to expand...

Are you talking about the place on the left on the second picture? If so thats a weld line where years back it started to crack,im not saying there is no hook cause i havent put a straight edge on it.
 
F

Fed

Commander
Joined
Apr 1, 2010
Messages
2,457
Re: Prop blow out, needing help

No, I'm looking straight up along the length of the keel.
 
J

jbeener1

Petty Officer 2nd Class
Joined
May 17, 2013
Messages
122
Re: Prop blow out, needing help

Sea Rider said:
Before investing blindless on a new prop or even modifying current one, you must test best engine/transom height match on flat calm, no wind waters. Having dialed sweet best height, combo will work well on almost all water conditions. Once you have finishes this height test, install an induction tach, go for a wot spin with you alone and light loaded boat and check max achieved rpm, compare numbers to wot factory stated engine parameters to know if over or under propped. Then can play with +,- 4 blades pitches and pick the one that will give near or top wot rpm for that engine.

Happy Boating
Click to expand...
Are you talking about raiseing the motor up the transom or adjusting tilt on the motor? If i raise it on the transom wont that make the blow out worse?
 
S

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Prop blow out, needing help

A few years ago someone added smart tabs to their boat close in to the motor as it was the only place for them.
As an added bonus they eliminated all of his venting problems.
Perhaps you could fashion a metal plate to go on the anti vent plate.
Try it on top and or underneath.
 
Last edited:
J

jbeener1

Petty Officer 2nd Class
Joined
May 17, 2013
Messages
122
Re: Prop blow out, needing help

steelespike said:
A few years ago someone added smart tabs to their boat close in to the motor as it was the only place for them.
As an added bonus they eliminated all of his venting problems.
Perhaps you could fashion a metal plate to go on the anti vent plate.
Try it on top and or underneath.
Click to expand...
Are you talking about something like a hydrofoil ?
 
You must log in or register to reply here.
Top