Reply
 
Thread Tools Search this Thread
 
Old 30 April 2011, 17:27   #1
Member
 
Country: UK - England
Town: bristol
Boat name: c2
Make: bombard
Length: 3m +
Engine: tohatsu 25hp
Join Date: Jul 2010
Posts: 33
Zapcat and tohatsu 25hp engine height on transom

i have a z10 gemini, and a 25hp yr 2000 M25C tohatsu.

have just mounted the engine normally, outboard bracket sitting on transom.
lots of splash from the engine, looks very inefficient.

the water level is hitting the square section of the lower leg and the shifter gear rod.

I have read about getting the engines as high as possible and can see that my engine needs to be higher so the lip above the anti cav plate is on the water line, not sure what that is called on the engine leg but it looks a smaller anti cav type plate.

The boat seems to take a while to plane and is highly sensitive to weight in the boat. I will mostly be running with 3 people in it so need to adjust for this setup.

On the back of the boat in the aluminim transom is a curved cut out that is shaped the same as the lip above the anit cav plate. Should these 2 be lined up?

what other marks can i use? when planing the deck of the boat isnt very high above the water line unlike the videos i have seen of the racing zapcats where you can jut see the outboard leg only beneath the boat and no part of the deck touching the water

I did some turns and the prop seemed to cavitate a bit so raising the motor will surely only make cavitation worse???
i am running a standard prop so not wanting it to come out of the water like the semi cleavers.

any help on engine height will be appreciated!
pics too ideal.


thanks
__________________

__________________
Commando C2 is offline   Reply With Quote
Old 01 May 2011, 03:47   #2
Member
 
Country: UK - England
Town: London
Boat name: Janey
Make: Zodiac
Length: 4m +
Engine: Outboard Yamaha 20hp
Join Date: Apr 2011
Posts: 47
Hi Mate,
I've only ever seen these with 50's on. Is your engine the right shaft length? Short, Standard or Long? The reason they get high out of the water is the speed they plane at so your 25 may not be quite up to the task.
It'll still move about, but won't offer the sheer terror that you can get with a 50. Also look at getting a Dolefin on there.
The Cav plate should be well under the water otherwise it won't be very efficient.
__________________

__________________
Bighag7 is offline   Reply With Quote
Old 01 May 2011, 12:28   #3
Member
 
Country: UK - England
Town: bristol
Boat name: c2
Make: bombard
Length: 3m +
Engine: tohatsu 25hp
Join Date: Jul 2010
Posts: 33
transom height

hi
thanks for that reply. my engine is a short/standard shaft. not sure if those two are one and the same or different lengths of shaft.
I have used the 25hp on my commando c2 3.5m sib and it planed ok.
When i took the zapcat out the other week it did plane and the faster i went the more the boat liked it and the bow lift from the nose cone kicked in more. There was just alot of spray from the square part of the engine leg hitting the water rather than the tapered part.

I have some dole fins so may give them a go as on the sib they made it plane really quick but seemed to cause more drag at speed due to them cutting through the surface of the water.
i am trying to find some pics of a zapcat with a 50 hp on it or a 40hp so can see where the tapered part of the engine leg is in relation to the bottom of the transom.
attached are 2 pics of the engine in its original postion just mounted straight onto the transom...
Attached Thumbnails
Click image for larger version

Name:	P1010315.jpg
Views:	378
Size:	64.8 KB
ID:	58964   Click image for larger version

Name:	P1010316.jpg
Views:	502
Size:	63.5 KB
ID:	58965  
__________________
Commando C2 is offline   Reply With Quote
Old 01 May 2011, 12:35   #4
Member
 
Country: UK - England
Town: bristol
Boat name: c2
Make: bombard
Length: 3m +
Engine: tohatsu 25hp
Join Date: Jul 2010
Posts: 33
cav plate

i have seen on some sites that the cav plate should be level with the water when running at speed?

here is the position of the engine raised up just enough so the tapered part of the engine is on line with the bottom of the transom and the curved cut out in the middle of the back of the transom!!

not had chance to try it out yet though.

if anyone has a short shaft 2 stroke tiller steer for sale let me know!!
thanks
Attached Thumbnails
Click image for larger version

Name:	P1010307.jpg
Views:	309
Size:	40.4 KB
ID:	58966   Click image for larger version

Name:	P1010306.jpg
Views:	321
Size:	59.1 KB
ID:	58967  
__________________
Commando C2 is offline   Reply With Quote
Old 01 May 2011, 13:17   #5
Member
 
Country: UK - N Ireland
Town: Bangor,Co Down
Make: Gemini/ Avon
Length: 4m +
Join Date: Jul 2003
Posts: 166
PM sent
__________________
Slaphead is offline   Reply With Quote
Old 01 May 2011, 15:24   #6
Member
 
Country: UK - England
Town: London
Boat name: Janey
Make: Zodiac
Length: 4m +
Engine: Outboard Yamaha 20hp
Join Date: Apr 2011
Posts: 47
Hi Mate,
Short shaft and standard are different. These boats only really come to life with 40 or more on the back although I saw a nutter with a 70 on the back once.
Keep tinkering and look at Youtube they have it all on there.
__________________
Bighag7 is offline   Reply With Quote
Old 02 May 2011, 13:04   #7
Member
 
Country: UK - England
Town: bristol
Boat name: c2
Make: bombard
Length: 3m +
Engine: tohatsu 25hp
Join Date: Jul 2010
Posts: 33
thanks bighag7

i was hoping the 25 would be enough with only 2 on board so will tinker with the height and see what happens.
Been on the look out for a 40hp but they are considerably heavier than the 52kgs of my 25hp so i will struggle to mount it on the boat on my own.!!

cheers
__________________
Commando C2 is offline   Reply With Quote
Old 02 May 2011, 14:11   #8
Member
 
m chappelow's Avatar
 
Country: UK - England
Town: yorkshire
Boat name: little vicky
Make: avon ex RNLI
Length: 3m +
Engine: tohatsu
Join Date: Mar 2008
Posts: 2,310
Quote:
Originally Posted by Commando C2 View Post
i have a z10 gemini, and a 25hp yr 2000 M25C tohatsu.

.

the water level is hitting the square section of the lower leg and the shifter gear rod.
try shape a block of wood and cable tie it in place like i did .
reason is my boats a short to standard and the engine is from my other boat thats a long ,after i put the block of wood in place i did away with the rubber spray sheilds that you can see in the pic .
Attached Thumbnails
Click image for larger version

Name:	114.jpg
Views:	320
Size:	74.3 KB
ID:	59019   Click image for larger version

Name:	redcar 08 068.jpg
Views:	325
Size:	67.6 KB
ID:	59020  
__________________
m chappelow is offline   Reply With Quote
Old 02 May 2011, 15:07   #9
Member
 
Country: UK - England
Town: London
Boat name: Janey
Make: Zodiac
Length: 4m +
Engine: Outboard Yamaha 20hp
Join Date: Apr 2011
Posts: 47
Hi Mate,
Try these guys, they're really fantastic and they have some reasonably priced 40s in.
http://www.billhigham.co.uk/used_dat...sed%20outboard

There is a tough plastic transom height adjuster that I've seen. It just drops on top of the transom and gives some extra height if you need it.
__________________
Bighag7 is offline   Reply With Quote
Old 02 May 2011, 16:54   #10
Member
 
Country: UK - England
Town: bristol
Boat name: c2
Make: bombard
Length: 3m +
Engine: tohatsu 25hp
Join Date: Jul 2010
Posts: 33
thanks for the info

The bit of wood at the front is a good idea, will look into it.

Looking at way less than a grand for a 40hp really. i am a bargain basement boater!!
have book marked the site though to keep looking regularly.

cheers
__________________

__________________
Commando C2 is offline   Reply With Quote
Reply

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





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 07:17.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.