Engine height as motor is setback.....

[Tom Foley]

I have to build an engine bracket for an old Wellcraft Pioneer which has a shallow vee hull . The bracket will be setback from the transom 36 inches and will have twin 25 " Merc 200 's on it . This is not a high performance boat , just looking for a rule of thumb or ratio of height vs setback . I have the original bracket to work with for a model but the new bracket will be much beefier for this twin deal .

[150aintenuff]

1" up for 6" back from V of hull.... i would personally find 20" mids for the 200's...

[tigweld]

<TABLE class=tborder style="BORDER-TOP-WIDTH: 0px" cellSpacing=1 cellPadding=6 width="100%" align=center border=0><TBODY><TR title="Post 1106241" vAlign=top><TD class=alt1 align=middle width=125>150aintenuff</TD><TD class=alt2>1" up for 6" back from V of hull.... i would personally find 20" mids for the 200's...
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Why would you want 20" mids on an salt water fishing boat?:rolleyes: .

29-30" up, at each engine centerline. will be a good starting point for the bracket for twins with 25" mids.

Marc

[kimswang]

I have to build an engine bracket for an old Wellcraft Pioneer which has a shallow vee hull . The bracket will be setback from the transom 36 inches and will have twin 25 " Merc 200 's on it . This is not a high performance boat , just looking for a rule of thumb or ratio of height vs setback . I have the original bracket to work with for a model but the new bracket will be much beefier for this twin deal .

Just been down that road myself, and haven't reached the end of it yet. What we have come up with is that water rise aprox 1" for every 8" of setback at aprox 70MPH. I had my twins on a Scarab where the pad was 5" above with a 38" setback. Now I have to dial in a triple V8 setup which obviously is a little more time consuming with two different heights. Stick with your 25" mids, the 20" might look good but your engines go under water every time you come off plane (at least my reason for not going 20" on my outers....) Good luck and feel free to post any test result you will come up with, as will I.

[150aintenuff]

<TABLE class=tborder style="BORDER-TOP-WIDTH: 0px" cellSpacing=1 cellPadding=6 width="100%" align=center border=0><TBODY><TR title="Post 1106241" vAlign=top><TD class=alt1 align=middle width=125>150aintenuff</TD><TD class=alt2>1" up for 6" back from V of hull.... i would personally find 20" mids for the 200's...
</TD></TR></TBODY></TABLE>
Why would you want 20" mids on an salt water fishing boat?:rolleyes: .

29-30" up, at each engine centerline. will be a good starting point for the bracket for twins with 25" mids.

Marc

slightly lower center of gravity, and more bracket support as motors arent hangig off the highest bolts with 3" of bracket in the air doing nothing.. end result is same hght with easier fishing around the cowls

[Tom Foley]

Thanks for the replies , this is not my boat and it is a tank ! I just want to get close on the height and get this thing out of my life !

[Tony Montana]

remember, if not using surface piercing LU, you want to try to get the cav plate above the prop just out of the water when running, not the centerline of the lower unit

[150aintenuff]

, you want to try to get the cav plate above the prop just out of the water when running, not the centerline of the lower unit

that is about right... there may be more room there speed wise and lift wise but its a fissin boat so they probably dont care just get it to run clean with the cav plates just above the surface and call it good... 30" or so will be where it ends up...

[Skater 32]

Does anyone know from exp on drive height with 24 degree non stepped bottom ? I have an imco box with a imco 2 inch shortie , the propshaft centerline is 2 inches below bottom. I run a hydo quad 4 x and it runs best with hardly any trim , and has never cavitated. Simply put how high is to high in regards to propshaft to bottom relation with 12 inch stand off box ?

[150aintenuff]

Does anyone know from exp on drive height with 24 degree non stepped bottom ? I have an imco box with a imco 2 inch shortie , the propshaft centerline is 2 inches below bottom. I run a hydo quad 4 x and it runs best with hardly any trim , and has never cavitated. Simply put how high is to high in regards to propshaft to bottom relation with 12 inch stand off box ?

how fast, how much trim does it take to lift the bow. and what hull... some have longer running surfaces and need to be deeper than others to lift.