|
|
31-07-2005, 08:29 PM
|
#1
|
Registered User
Country: England
Location: Poole
Occupation: Diesel
Boat make: Phantom 25
Engines: 2 x 260 Efi Offshore
Cruising area: Poole
Join Date: Mar 2005
Location: Poole
Posts: 203
|
Engine height
Any comments on the height of the engines??
__________________
|
|
|
31-07-2005, 09:09 PM
|
#2
|
Registered User
Country: Essex
Location: Great Stambridge Essex
Occupation: Director Paving company
Interests: Boating/Squash
Cruising area: Essex Marina/crouch southeast coast
Join Date: Sep 2004
Location: Great Stambridge Essex
Posts: 2,033
|
Looks a inch to high to me but im no expert ive always fought the bullet should be in line with the bottom of the boat
__________________
__________________
[
|
|
|
31-07-2005, 09:15 PM
|
#3
|
Registered User
Country: England
Location: Poole
Occupation: Diesel
Boat make: Phantom 25
Engines: 2 x 260 Efi Offshore
Cruising area: Poole
Join Date: Mar 2005
Location: Poole
Posts: 203
|
Theye have a set back of 6 inches whether that makes a difference?
|
|
|
31-07-2005, 09:51 PM
|
#4
|
Registered User
Country: England
Location: Surrey
Occupation: Subsea Design Engineer
Boat name: The Mutz Nuts/Beyond Obsession/HoneyRider
Boat make: Phantom 20, Phantom 25, Cigarette 39 TopGun Unlimited
Engines: Mercury Promax 300 Madefi, Twin Mercury 200XS, Twin Merc Racing 525 EFI's
Cruising area: Eastney/Portsmouth
Join Date: Feb 2005
Location: Surrey
Posts: 757
|
Cye says that for every 4" setback you go up 1"
|
|
|
31-07-2005, 10:09 PM
|
#5
|
Registered User
Join Date: Mar 2004
Posts: 6,891
|
Running 2 high has a number of side effects:
1) Loss of water pressure
2) Loss of bow lift
3) Difficulty getting on the plane.
4) Loss of drive in the rough
But the upside is el maximo speedo in the flat.
2 high, 2 low. Dunno till you've tried it. If it were me I'd start conservative and go a bit lower, then jack em up if needed.
|
|
|
31-07-2005, 10:09 PM
|
#6
|
Registered User
Country: England
Location: Poole
Occupation: Diesel
Boat make: Phantom 25
Engines: 2 x 260 Efi Offshore
Cruising area: Poole
Join Date: Mar 2005
Location: Poole
Posts: 203
|
That looks about right then.
Thanks
|
|
|
31-07-2005, 11:16 PM
|
#7
|
Registered User
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer
Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
|
Jay Smith on scream and fly (the guy building my engine) says
Propshaft height from pad
--------------------------------------------------------------------------------
I have always used the formula for every 1" you go back you can go up 1/8" from split shaft..... In otherwords if you have a 8" plate you can ( in theory ) come up 8/8 ths or 1 " If have used this formula on many different configeration hulls and its been pretty close give or take 1/4"........You need to remember all hulls have thier own sweet spots and its got alot to do with the layup weights and the load its carrying...
Good luck !
Jay
|
|
|
31-07-2005, 11:33 PM
|
#8
|
hello
Join Date: Mar 2004
Posts: 2,739
|
Quote:
Originally posted by Taz
Looks a inch to high to me but im no expert ive always fought the bullet should be in line with the bottom of the boat
|
Don't forget its a twin, so its the bottom of the boat directly infront of each motor and not the bottom of the V. Bearing this in mind its actually very difficult to judge the engine heights from that side on 2D photo.
|
|
|
01-08-2005, 11:48 AM
|
#9
|
Registered User
Country: England
Location: Poole
Occupation: Diesel
Boat make: Phantom 25
Engines: 2 x 260 Efi Offshore
Cruising area: Poole
Join Date: Mar 2005
Location: Poole
Posts: 203
|
Engine height
Quote:
Originally posted by Johnny Boat Dude
Don't forget its a twin, so its the bottom of the boat directly infront of each motor and not the bottom of the V. Bearing this in mind its actually very difficult to judge the engine heights from that side on 2D photo.
|
I have placed a straight edge along the underside of the hull to the torpedo of the gearbox. Theye are 3/4" up & the engines are set back 6". I am not to bothered about top end more so the handling, (this should be a good rough weather boat) I have put strenghtheners from the transom through the splash well then bolted through the Knees.
All i know is that it ran a few years ago with CLE boxes but I do not know what it ran like, it was the P25 @ DB Marine
John
|
|
|
01-08-2005, 12:05 PM
|
#10
|
Registered User
Join Date: Jun 2005
Posts: 276
|
Looks like an OK starting point - if not a good final position - only testing will tell for sure!
If yr going to bias the boat towards better rough water handling (vs out & out speed) then make sure you've got some room to manouvere the engines down some more. Then if yr initial testing gives unsatisfactory handling its easy to drop the engine down to the next hole on the saddle.
Hope this helps - let us know how it goes
BTW what's running from this pick up?
|
|
|
01-08-2005, 12:08 PM
|
#11
|
Registered User
Country: England
Location: Poole
Occupation: Diesel
Boat make: Phantom 25
Engines: 2 x 260 Efi Offshore
Cruising area: Poole
Join Date: Mar 2005
Location: Poole
Posts: 203
|
Gaffrig Speedo & Thanks for the Info
John
|
|
|
01-08-2005, 12:33 PM
|
#12
|
Senior Member
Country: England
Location: Warsash
Occupation: Boat Designer
Interests: sport
Boat name: Santana
Join Date: Mar 2004
Location: Warsash
Posts: 1,838
|
All looks pretty good Jon - don't think you will have any major problems, water pressure should be good. If handling is out at all you may look at going a little lower as you should have plenty of top end anyway.
Probably all going to go down to what props you run and getting those dialled in.
Adam
|
|
|
01-08-2005, 12:47 PM
|
#13
|
Registered User
Country: England
Location: Poole
Occupation: Diesel
Boat make: Phantom 25
Engines: 2 x 260 Efi Offshore
Cruising area: Poole
Join Date: Mar 2005
Location: Poole
Posts: 203
|
Cheers Adam
Prop's what a choice I am thinking about a 5 blade clever but am open to Suggjestions but it really depends on how many people are willing to lend me a pair of props until I get the right one!! but that will be next year
John
|
|
|
01-08-2005, 01:04 PM
|
#14
|
Registered User
Location: GOLDEN MILE
Boat name: LILY THE PINK AND TERMINATOR 11
Boat make: PHANTOM 21 AND 20
Engines: 2.5 EFI X 2
Join Date: Mar 2004
Location: GOLDEN MILE
Posts: 2,475
|
ive got a pair of 24 and 28 choppers your welcome to borrow
__________________
PLEASE DON'T STEAL...THE GOVERNMENT DON'T LIKE THE COMPETITION
|
|
|
01-08-2005, 01:28 PM
|
#15
|
Registered User
Country: England
Location: Poole
Occupation: Diesel
Boat make: Phantom 25
Engines: 2 x 260 Efi Offshore
Cruising area: Poole
Join Date: Mar 2005
Location: Poole
Posts: 203
|
Thanks I will take you up on that when I get there.
John
|
|
|
14-08-2005, 09:47 PM
|
#16
|
Registered User
Country: Norway
Location: Lillesand
Boat make: Phantom 25
Engines: PM 300 SVS
Join Date: Aug 2005
Location: Lillesand
Posts: 8
|
Engine height
Hi!
Glad to see someone else also rigging twins on a Phantom 25! I am also in a process of mounting twins on my 1985 Phantom 25. It will either be 2 x Merc 2.5 or 2 x Promax 300 SVS.
I have been reccommended to mount the engines 23 inches senterline to senterline. How far is your engines mounted from eachother?
Merc Hi Performance reccommend a engine mounting height of 7 inches - 8 inches using twins in excess of 90 mph. This translates to a propshaftheight of approx. 1 inch below - even with the bottom. So you should be on the spot there.
If I am to use 2 x PM 300, I have to mount the engines as close as possible to the transom due to the overall balance. Then the mounting height will be cruical. I have to find a balance between rough water handling and top speed. I presume 1 inch below will be the solution for a start.
What kind of speed do you expect from your rig? Any pictures?
Cheeers from Norway!
Toffen G
|
|
|
14-08-2005, 10:09 PM
|
#17
|
The Doc
Join Date: Mar 2004
Posts: 8,291
|
Toffen.
how far are you into this project?
|
|
|
14-08-2005, 10:24 PM
|
#18
|
Registered User
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer
Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
|
by the sounds of it not very far if he hasn't even got the motors yet
|
|
|
14-08-2005, 10:25 PM
|
#19
|
Registered User
Country: Norway
Location: Lillesand
Boat make: Phantom 25
Engines: PM 300 SVS
Join Date: Aug 2005
Location: Lillesand
Posts: 8
|
Engine height
Hi!
I had twin Merc 2,5 SS engines available this spring, but due to the taxman, I had to postspone it some months.
I have 2 x Merc 2.5 with 20 inch midsections available now, but then I have to sell my PM 300 SVS. Therefore I may buy a nice 2000 PM 300 (run in fresh water only) with 20 inch midsection and sportmaster lowers.
I have through some research learned that the engines should be mounted 23 inches senterline to senterline (alien cowlings). I will use Latham / Marine Machine hydraulic steering.
If I am to use 20 inch midsections, I am afraid I am to low with the propshaft. The transom is 22,5 inches tall at 23 inches senterline to senterline. With a 20 inch midsections, the engine mounting height will be only 2,5 inches. Therefore the engines have to be lifted approx. 4,5 inches.... A 15 inch midsection (SS / Mad Efi) could be the solution. But then we may be too high. What do you think.
I expect a speed of 90 mph +. Should this be possible.
Here is a picture of the ol'lady.
Cheeers and thanks, Toffen G
|
|
|
14-08-2005, 10:37 PM
|
#20
|
The Doc
Join Date: Mar 2004
Posts: 8,291
|
I'm quite obviousely underqualified to answer those questions.
just a thought............dont bother with aliens if it makes set-up a problem. Also, havent people rigged Phantom 25's with 20inch mids before and had good results?
CC
__________________
|
|
|
|
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|
» Recent Threads |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|