Planing Birchwoods

[Guest]

Can anyone out there help with a problem I have with a 22ft Birchwood (1976) fitted with a 115 hp Volvo Penta petrol engine and outdrive.

The boat refuses to rise onto the plane despite :

Checking the usual - standard fitment with no excessive weight, clean hull, full water tank in the bow.

Volvo have run a check on the size of propellor, which has now been changeed to a 13 x 8 on their recommendation (incidentally they also said the boat should be capable of 20 knots)

The outdrive has been trimmed fully under to give lift to the stern

The engine is in sound mechanical order but I am fitting electronic ignition and changing from unleaded back to leaded (LRP) petrol.

On our last outing the boat reached 12 knots at 4,200 revs with the bow high in the air and the stern dug in.

The boat is not fitted with trim tabs and I do not want to go to the expense of hydraulic flaps.

Has anyone any suggsetions ?

Alastair

 

[longjohnsilver]

Have you tried more weight in the bow just to get you on the plane. People are the best as you can move them around easier. I would have thought that a 115hp is maybe a bit on the small side for the size of boat, if it's an interceptor then I imagine it's a fairly heavy lump.

 

[hlb]

Long Johns idea is best and cheapest, but think of fixed trim tabs, like bent bits of mettal bolted on or better still an adjusting bolt to change them till best effect then just weld the bugger up.

Haydn

 

[byron]

The Interceptor Junior 22 (To give its full name) had two engine options, your option being the smallest. The 130hp the biggest. Now some quarter of a century later you are expecting too much of the gal. When new she weighed a little over 3000 Lbs, I wonder what she weighs now with all the additions, fenders, etc. etc. I doubt that even when the engine was new she did more than 18 knots on a good day. Are you trying her on salt water or fresh? It makes a deal of difference.
You might coax her up on the plane by chucking weight forward, are you sure of 14 knots? because she should be trying to get over the hump at about 11/12 knots.

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[Guest]

Don't know the boat. Do know that it is all v weight sensitive. Empty the water (20gals = 200lbs=massive person) , and go out with wife only in saloon at bow. Also leave anything heavy on pontoon, dinghy etc.

 

[Guest]

Try retarding the ignition timing by a couple of degrees....

 

[andrewbarker]

Given your occupation should you really be going any faster?
Try the usual enginey things - Castrol RS racing oil to reduce friction, ZX1 oil additive, Nitrox Hot shots petrol additive, new plug leads & Super4/splitfire plugs.

 

[Guest]

I ask the following as a novice
What is the effect of salt water v other?
Would not putting weight forward prevent planing?

RJMW

 

[ArthurWood]

I agree with Longjohn, ie the boat sounds underpowered. For comparison I have a 1987 19ft Wellcraft, 2500lb unladen, with 165hp Merc and it flies (when no anti-freeze is pouring out of it). Is it possible to fit a hydrofoil to the anti-cavitation plate?
They make a tremendous difference to time to get on plane. And they are v. inexpensive. A combination of shifting weight forward and the hydrofoil might do the trick.

 

[scottie]

AQ115 IS JUST NOT BEEFY ENOUGH

SEE IF YOU CAN GET A SET OF CARBS AND MANIFOLD FROM AQ130
SHOULD BE PLENTY BREAKING NOW
INFACT IF YOU CAN GET IT THE HEAD AS WELL WOULD BE EASIER
CHECK THE HEAD GASKET A STHEY COME IN VARIOUS THICKNESSES AND VARY THE COMPRESSION RATUO
EARLY 130 CAME WITH 100 DRIVE I THINK SO DRIVE SHOULD TAKE THE POWER

 

[byron]

why are you shouting?

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[scottie]

cos my cap lock was stuck on

 

[byron]

RJMW., salt water is more bouyant than fresh consequently a vessel has more ready made lift. Any planing vessel will move faster in salt water than fresh by a significant margin.
Try this, measure your freeboard in fresh water and then again in salt water. At the extreme consider swimming in a lake and swimming in the Dead Sea.
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www.alexander-advertising.co.uk<P ID="edit"><FONT SIZE=-1>Edited by byron on Tue Nov 20 15:11:16 2001 (server time).</FONT></P>

 

[BarryD]

Bit personal Byron - measure your freeboard before and after going swimming!

 

[scottie]

Re: new users

I new what you meant when you said it but give us abreak you want us to join in but and hit us with your superior knowledge when we make a mistake

are tin hats standard issue?

 

[BarryD]

In defence of Byron

Capital letters are considered bad SHOUTING form anywhere on the internet - the question was why are you shouting. You're answer was valid - no problem. Of course if you only type by looking at the keyboard and never at the screen then this makes sense. If not then...

Your advice sounds fine though! Keep pitching in...
<P ID="edit"><FONT SIZE=-1>Edited by BarryD on Tue Nov 20 15:23:03 2001 (server time).</FONT></P>

 

[Guest]

Re: sorry!! no offence

I must apol on be½ of Byron. I was not gonna say a thing. BUT IT DOES LOOK A BIT LIKE , ahem , shouting. Anyway, soddit, I have done much worse. Oh, and fat-finger crap typing is ok. And welcome. Where are you/boat btw?

 

[byron]

Re: new users

Sorry Scottie, I have just slapped my own wrist on your behalf. I just typed without thinking, no offense mate

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[byron]

OK OK so I got a weight problem. I'm still pretty though in a chubular way ;-)

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[BarryD]

Not a comment on your waist Byron (see my photos for - Pot / Kettle Black etc..) more your instructions to RJMW to measure his freeboard <G>