Reply
 
Thread Tools Search this Thread
 
Old 09 February 2020, 02:11   #1
Member
 
beerbelly's Avatar
 
Country: UK - England
Town: teesside
Boat name: magic
Make: humber 5.5
Length: 5m +
Engine: mercury 100
MMSI: 232012453
Join Date: Apr 2014
Posts: 1,161
outboard mounting hight problem

hi folks I have just taken delivery of a new Humber destroyer 5.5 and the first problem while rigging it has arisen .my outboard turns out to be a 25inch leg and my transom is only 21.5 inch I know but here I am .I have hung it on the lowest mounting holes and the vent plate is approx. 5mm below the keel line and the outboard is on its highest setting .will this be ok or should I buy a jack plate such as

https://www.ebay.co.uk/itm/CMC-Stati...EAAOSwK-1dH3el

I don't want to buy another outboard as quite frankly I cant afford one and this mercury f100 has less than 50 hours and runs sweet as ( it looks like it was mounted quite low on the valiant I took it off and was ok if a little slow at 35knts . thanks
__________________

__________________
beerbelly is offline   Reply With Quote
Old 09 February 2020, 02:14   #2
Member
 
beerbelly's Avatar
 
Country: UK - England
Town: teesside
Boat name: magic
Make: humber 5.5
Length: 5m +
Engine: mercury 100
MMSI: 232012453
Join Date: Apr 2014
Posts: 1,161
a pic of the outboard hight. sorry its on its side cant figure out how to rotate it
Attached Thumbnails
Click image for larger version

Name:	20200208_165012.jpg
Views:	134
Size:	123.6 KB
ID:	132099  
__________________

__________________
beerbelly is offline   Reply With Quote
Old 09 February 2020, 04:27   #3
Member
 
Country: Ireland
Town: Ennis
Boat name: pac 22
Make: Halmatic
Length: 6m +
Engine: inboard
Join Date: Aug 2018
Posts: 114
ideally the plate should be level with the bottom profile of the boat. I cant see 5mm making a huge difference to performance especially if you can still trim it.
There is only one way to find out though and that's a sea trial.
__________________
mikehhogg is offline   Reply With Quote
Old 09 February 2020, 04:54   #4
Member
 
Country: UK - England
Town: Winchester
Boat name: The Bandit
Make: Ribtec 535
Length: 5m +
Engine: Yamaha 90 2-Stroke
Join Date: May 2009
Posts: 496
^^^ pretty much what I was going to say, just try it - although not today I might suggest.

If it works ok I would make a neat plug to fill the gap and make it look intended to the untrained eye.

Best of luck with it.
__________________
Ribtecer is online now   Reply With Quote
Old 09 February 2020, 05:03   #5
Member
 
Country: UK - Scotland
Town: north ayrshire
Boat name: charlie girl
Make: reiver 3.8/regal3760
Length: 10m +
Engine: 40hp 2st 2x6lp 315
Join Date: Jul 2009
Posts: 2,445
Idealy you would have the av plate slightly above the keel line for least drag and best performance. I usually start fitting about 1"up from level and adjust from there after sea trail, rarely do you need to go down. Occasionally you can go up and gain a knot or so dependingin the boat. That said if yours is a little deep and you lose a knot or two without any unusual handling tendencies then probably an acceptable compromise.
As others have said take it out and try it see how it goes
__________________
beamishken is online now   Reply With Quote
Old 09 February 2020, 05:25   #6
Member
 
beerbelly's Avatar
 
Country: UK - England
Town: teesside
Boat name: magic
Make: humber 5.5
Length: 5m +
Engine: mercury 100
MMSI: 232012453
Join Date: Apr 2014
Posts: 1,161
thanks folks yes I am going to try it before deciding what to do .and no it wont be today still a few jobs to do yet
__________________
beerbelly is offline   Reply With Quote
Old 09 February 2020, 06:00   #7
Member
 
Country: UK - England
Town: Winchester
Boat name: The Bandit
Make: Ribtec 535
Length: 5m +
Engine: Yamaha 90 2-Stroke
Join Date: May 2009
Posts: 496
With a 100hp on a 5.5, I don't think a loss of a knot will be noticeable.

You'll be to busy trying to hang on.
__________________
Ribtecer is online now   Reply With Quote
Old 09 February 2020, 06:16   #8
Member
 
beerbelly's Avatar
 
Country: UK - England
Town: teesside
Boat name: magic
Make: humber 5.5
Length: 5m +
Engine: mercury 100
MMSI: 232012453
Join Date: Apr 2014
Posts: 1,161
thanks I was thinking to get the jack plate even if its just to add some reinforcement to the part of the saddle unsupported above the transom
__________________
beerbelly is offline   Reply With Quote
Old 09 February 2020, 06:24   #9
Member
 
Country: UK - England
Town: Winchester
Boat name: The Bandit
Make: Ribtec 535
Length: 5m +
Engine: Yamaha 90 2-Stroke
Join Date: May 2009
Posts: 496
Quote:
Originally Posted by beerbelly View Post
thanks I was thinking to get the jack plate even if its just to add some reinforcement to the part of the saddle unsupported above the transom
Take it out and give it a gentle test, if all is good that could be a worthwhile avenue to explore to help support for rougher harder conditions.
__________________
Ribtecer is online now   Reply With Quote
Old 09 February 2020, 06:36   #10
Member
 
Country: UK - England
Town: Retford
Boat name: Spy-sea-one
Make: Excel 435
Length: 4m +
Engine: Suzuki Outboard/25/4
Join Date: Oct 2011
Posts: 5,917
not as you but my new sib is the same 10 mm below keel not tested yet but i'm not expecting any significant difference. for you the jack plate will sort it in any case BB
__________________
jeffstevens763@g is offline   Reply With Quote
Old 09 February 2020, 09:42   #11
Member
 
Locozodiac's Avatar
 
Country: Other
Town: Lima-Peru
Boat name: Nautile
Make: Sea Rider 450 Rib
Length: 4m +
Engine: Tohatsu 5/18/30 HP
Join Date: Sep 2007
Posts: 1,971
Post a picture of the lower leg shot sideways....

Happy Boating
__________________
Locozodiac is offline   Reply With Quote
Old 09 February 2020, 11:48   #12
Member
 
Phil M's Avatar
 
Country: UK - England
Town: Whitehaven
Boat name: Cerberus
Make: Destroyer 5.8
Length: 5m +
Engine: 115hp Merc 4st
Join Date: Oct 2012
Posts: 462
My anti cav plate on my 5.8 is about 20mm above the keel line and I still think it could go a little higher. I think you'll get quite a lot of water shown up with it that low. I had the other problem as the 20" transom was nearer 22" so I can't go any lower.

Phil M
__________________
Phil M is offline   Reply With Quote
Old 09 February 2020, 15:33   #13
Member
 
Last Tango's Avatar
 
Country: UK - Scotland
Town: Denny
Boat name: Hebridean Storm
Make: Coastline
Length: 6m +
Engine: Mariner F150
MMSI: 235107505
Join Date: Mar 2013
Posts: 1,579
As everyone has said......give it a try.
"If it ain't broke don't fix it"
__________________
Last Tango is offline   Reply With Quote
Old 10 February 2020, 12:48   #14
Member
 
Country: Canada
Town: Tiverton,Nova Scotia
Make: various
Length: 7m +
Engine: various
Join Date: Feb 2005
Posts: 152
just remember if you have steering by cable/rod, you might need a new one, adding jackplate (been there, done that), ie. you might need a few more inches ... possibly not if you have hydraulic steering lines.
__________________
tiverton_tom is offline   Reply With Quote
Old 10 February 2020, 12:54   #15
Member
 
Country: Canada
Town: Tiverton,Nova Scotia
Make: various
Length: 7m +
Engine: various
Join Date: Feb 2005
Posts: 152
this is from a Facebook post on topic of proper mounting height (options)

https://www.facebook.com/photo.php?f...type=3&theater
__________________
tiverton_tom is offline   Reply With Quote
Old 10 February 2020, 13:05   #16
Member
 
Country: Canada
Town: Tiverton,Nova Scotia
Make: various
Length: 7m +
Engine: various
Join Date: Feb 2005
Posts: 152
this was original post:

https://www.facebook.com/groups/1310...20894034609777
__________________
tiverton_tom is offline   Reply With Quote
Old 12 February 2020, 12:15   #17
Member
 
Country: USA
Town: Moab
Boat name: Solgear
Make: Avon
Length: 4m +
Engine: Outboard
Join Date: Jul 2019
Posts: 24
RIBase
I have taken a 2 transoms built for a short shaft and converted them into transoms for a long shaft. I used plywood glued together and then resin coated and cut out to fit perfectly on the transom with the same width. Then I plate both the front and the back with aluminum covering the entire transom and cutting holes for the scuppers. This aluminum is through bolted in 4 corners, plus through bolts on the piece that holds the floor down, plus through bolts on the motor and I have struts that bolt to the floor and attach to the transom with through bolts. Every hole gets resin or 100% silicone at the least. The transom is more rigid than it was to begin with and with the struts I'm able to transfer energy through the boat and not work the transom so hard. I run these boats down class V rapids on the Colorado River.
__________________
Solgear is offline   Reply With Quote
Old 12 February 2020, 16:18   #18
Administrator
 
John Kennett's Avatar
 
Country: UK - England
Town: Brighton
Length: 3m +
Join Date: May 2000
Posts: 6,986
Quote:
Originally Posted by Solgear View Post
I run these boats down class V rapids on the Colorado River.

That sounds cool. Have you got any video?
__________________
John Kennett is offline   Reply With Quote
Old 26 April 2020, 11:02   #19
Member
 
beerbelly's Avatar
 
Country: UK - England
Town: teesside
Boat name: magic
Make: humber 5.5
Length: 5m +
Engine: mercury 100
MMSI: 232012453
Join Date: Apr 2014
Posts: 1,161
well I tried it. love the Humber a much more comfortable ride than the valiant was quite choppy with 30mph easterly's and a meter or so swell and it was comfortable around 20knt mark didn't go out far as we were filming some racing yachts but I am happy with the rib .unfortunately the outboard being low did make itself felt there was a lot of water splashing up around the transom and it felt flat we went into some flat water in the old Victoria dock and just couldn't get it over 32knts .so I have decided not to add the jack plates I have bought and risk my lovely shiny new outfit looking cobbled together I have bitten the bullet and put a deposit on a new 115 mariner. to be collected after the lockdown . oh all this testing was done before the travel restrictions
__________________
beerbelly is offline   Reply With Quote
Old 30 April 2020, 19:04   #20
Member
 
Locozodiac's Avatar
 
Country: Other
Town: Lima-Peru
Boat name: Nautile
Make: Sea Rider 450 Rib
Length: 4m +
Engine: Tohatsu 5/18/30 HP
Join Date: Sep 2007
Posts: 1,971
Installing an L Motor on a Medium Height Transom.-

Had same exact issue, my fast responder 430 Rib was not an S or L height transom, had excessive water splashes at back transom when on plane while being powered with a 2 strokes L 18 HP motor. Didn't wanted to install a transom mount or an exterior jack plate to rise the motor and lower leg as well, just a cheap device that would stop the excessive water splash. In a moment of true enlightenment and deep thinking turned duplicating the original lower fin with an epoxy putty.

The fake fin was tested at several lower leg heights till the water splash was totally canceled out, then glued to the final lower leg's front resting position with an aersospace glue, Works as a charm..

Happy Boating
Attached Thumbnails
Click image for larger version

Name:	430 Sib-Tohatsu 18.JPG
Views:	18
Size:	145.4 KB
ID:	132925   Click image for larger version

Name:	Back Water Splash.JPG
Views:	21
Size:	179.6 KB
ID:	132926   Click image for larger version

Name:	Fake Fin.JPG
Views:	21
Size:	169.4 KB
ID:	132927   Click image for larger version

Name:	Smooth Water Flow.JPG
Views:	19
Size:	182.9 KB
ID:	132928  
__________________

__________________
Locozodiac is offline   Reply With Quote
Reply

Tags
outboard

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




All times are GMT -5. The time now is 06:55.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.