Am I propped correctly?

[Skin diver]

I have a 20 foot boat with twin 70la's. With the boat loaded and 13 1/2 x 15 props I hit 5800 rpm at wot. Does this sound about right? If not what size props would you recommend?

[boscoe99]

Red line on that model is 6300. So, you could stand to go down in pitch by a couple of inches if you want.

How is the engine mounting height? Seems to be normal for most motors to come from a dealer and/or boat builder that are a tad on the low side. Ideally you should be able to see the upper surface of the anti-ventilation plate when at cruise and with the motor trimmed to the most efficient trim angle. Positioning a motor properly is a cost effective solution to getting a bit more performance.

Is there anything that makes you think that a pitch change is needed or desired? Going down in pitch should improve the time it takes to get onto plane if that is an issue for you.

[Skin diver]

Thanks for the quick response. I did raise my engine one hole up because there was a lot of spray from water hitting the engine. I still haven't checked the anti vent plate when running on plane. Motors are on a bracket so I'm kind of scared to hang out off the back to check. Next time out I'll check. As far as props, I just want to make sure I'm getting the best performance and fuel consumption possible. Would going down in pitch have an affect on fuel?

[boscoe99]

Thanks for the quick response. I did raise my engine one hole up because there was a lot of spray from water hitting the engine. I still haven't checked the anti vent plate when running on plane. Motors are on a bracket so I'm kind of scared to hang out off the back to check. Next time out I'll check. As far as props, I just want to make sure I'm getting the best performance and fuel consumption possible. Would going down in pitch have an affect on fuel?

Maybe. Maybe not. The thing with propellers is that they have to be tested to find out what works for any given owner of a particular boat and motor(s) combination. It takes effort and costs money.

There are hundreds of different brands, models and sizes (pitch and diameter) within a given model of propeller.

[99yam40]

where are you located?
I have read there is a company down in florida that will bring out different props and try them out on you rig to find the ones you want/need for a price

[Skin diver]

In the middle of nowhere. Hawaii. Shopping for props is crazy with all the different brands and makes. Not many choices here in Hawaii. Ordering from the mainland would be best but shipping kills the deal. How do you choose?

[boscoe99]

What brand, model and size of propeller is on the boat now?

What changes do you want other than improved fuel efficiency?

Being in Hawaii is worth not having a good propeller selection to choose from. What island are you on?

Given the depth of the water there I doubt you go far from shore for diving. But maybe you run from one island to another.

Fuel efficiency is going to be in the tenths of a gallon per hour. More than likely not worth a grand or more in the pricing for new propellers. But then gasoline is very high there. I paid $2.04 a gallon today here in Georgia. Some places are below two bucks.

[99yam40]

yea i thought I would never see gas under $2 @ gal again and it has been for many months now here in Tx

Check out Prop gods I think on the THT forums he may help you with all you info leading to the correct props

[SeaDawg3]

yup I second that, give Ken a shout...
Propgods.com > HOME

[Skin diver]

Okay thanks for your help. I think I'll just stick with the props I have as it does work alright even if I don't reach the max rpm's at wot. Gas here is about $3/gal for ethanol free gas. Pretty good as it was close to $5/gal about 6 months ago.

[99yam40]

will not hurt to contact ken and give him all your info to see what he says

[Skin diver]

Ok. I'll contact him and see. Thanks for all the help.

[Danishboater]

Here in Denmark gas are 2 bucks for a LITER

[boscoe99]

Here in Denmark gas are 2 bucks for a LITER

Yes, but you have free health care for life. Plus a lot of other benefits that we don't get over here.

I told you about my sister being married to a Dane. When he is here in the states and gasses up his rental car, he always make a comment about the fact that they are giving away gasoline down at the gas station.

[Danishboater]

Thats right,but we also pay worlds highest tax,and if we buy a car or a motorcycle who costs 10.000 bucks without license plates,we must pay extra 18.000 bucks for having license plates on it,and then pay 1200 bucks a year for driving on the roads!!!