AV plate height questions

[realmasa]

Hello,<br /><br />i'm going to buy a new prop, my old destroyed one was a Ballistic 14x21, the new one will most likely be a Turbo 1 14x21 with thinned leading edges, machined by the seller. I have not been able to check my current height of AV plate vs. bottom of the hull, because right now the engine is not in shape. <br />I've done some searching in the forums and the rule of thumb seems to be the AV plate even with bottom or up to 1 inch above. With the ballistic i think the engine height was pretty good(?), could ventilate in turns sometime and had high steering torque at higher speeds. Also poor ability to stay in plane<br />Now to my question, regardless of what the height is now, does the change of prop to Turbo 1 automatically gives me the option of raising the engine a bit higher? If it turns out that the AV plate is lower than the bottom of the hull now, is it "safe" to raise it so it's even, or even higher? <br />Once the boat is in water, it's not an easy undertake shifting height of the engine... Please note i have no jack plate and will not install one. Click the link to look at My Boat <br /> <br />Please let me know what you think.<br /><br />Thanks,<br />Mattias

 

[JB]

Re: AV plate height questions

Prop topic.

 

[WillyBWright]

Re: AV plate height questions

Even for average use with an average prop, down an inch for rough water operation, 1 inch up for speed. On a Bass Boat, Up. On Yours, even or down. By changing from a 3-blade to a 4-blade, you can shift that scale up an inch.

 

[realmasa]

Re: AV plate height questions

On Yours, even or down.

Is that because my hull is too v-shaped for the AV plate to be above the bottom? The bottom is about 2m/6.56 feet wide and the height difference between the bottom keel and the sides(at the stern) is about 40cm/1.31 feet

 

[gatorred]

Re: AV plate height questions

run it see what it like's try moving it up or down try 1/2 in at a time if posible

 

[Dhadley]

Re: AV plate height questions

Dont put a lot of money in a prop thats been modified. Especially one that has the blades thinned. No telling what else has been "improved".<br /><br />Keep in mind to not judge all Turbo's by one that's been altered.

 

[realmasa]

Re: AV plate height questions

Hi Dhadley,<br /><br />i'm not really following here. Wouldn't thinning leading edges always be an improvement? The shop i'm in contact with is located in Norway, and i'm sitting in Finland so it's either thinning or not, i can't test both.<br />The shop is Winrace.no and has a lot of racing experience and it's his(Olle Terjesen) 'advice' that he could do the thinning for a small fee. He said that the Ballistic is a fast and a good prop, so i guess he wanted the Turbo 1 to get an advantage <br />My spontaneous guess is that efficiency is improved because it allows the prop to cleave the water more easily. What are the potential drawbacks?<br />Also with your experience, what is your opinion on the AV plate height?<br /><br />Thanks,<br />Mattias

 

[WillyBWright]

Re: AV plate height questions

What conditions do you typically encounter and what are the worst you could encounter? If you go out in water that gets pretty well churned up, you want thet even or lower so the prop doesn't come out of the water with every wave. If it's only smooth water to a small chop, then even or up an inch. With a 4-blade prop, you can usually run a hole higher on the transom than normal.<br /><br />Thinning the blades can disrupt the designed water flow over the blades and unless done very precicely can actually reduce performance.

 

[realmasa]

Re: AV plate height questions

Hi Willy,<br /><br />thanks for your reply. I get your point with the AV plate height, however, i'm gonna wait until i can tilt down the engine and measure where it actually is.<br />To everybody; please input your opinions and ideas about thinning edges, bad and good experiences. If it's done, it will be machined by a professional.<br /><br />Thanks,<br />Mattias

 

[Dhadley]

Re: AV plate height questions

Thinning the blades is indeed an old race trick. However the trade off is that they tend to lose their shape quicker because of flexing. Most times that translates to loss of bow lift. <br /><br />The other side of that is we don't know what else was changed.