Apologies up-front for a fairly lengthy post - but the full story is
probably
necessary to make sense of the problem!

I have a Teal 22 which I'm led to believe was originally fitted with a Volvo
petrol engine on a Volvo outdrive. It still has the Volvo outdrive but is
now powered by a Perkins 399 diesel.

I raised a question in the NG last year regarding disappointing directional
stability - in particular a SIGNIFICANT degree of wandering at low speed.
As a result of various discussion I installed ballast (in the form of 5 x
25kg bags of pea shingle!) in the bow. If this resulted in any improvement
it
was marginal and only noticeable at higher speed.

Earlier in the season with three on board, at one point the largest
member of the crew (I'd guess ~20 stone) decided to sit in the roof of the
fore cabin for the return journey. This has a VERY significant impact - I
lined the boat up with
the middle of the river and, with a very slight infrequent adjustment to the
helm, it stayed on course - very desirable behaviour but never before
witnessed with this boat.

This suggested the yet more ballast was required in the bow -
and another 50 or 75kg was put in.

Unfortunately, the following week the (plastic) prop struck a submerged
object and was completely destroyed calling for a replacement. On having a
replacement fitted I was informed that the prop originally fitted had been
modified (not too well) from a much larger one and was in fact too small. A
replacement larger aluminium prop has now been fitted.

However, this has proved to be important as it has radically changed the
handling of the boat. The top speed has, I would guess, doubled - at
least 10-12mph. At normal cruising speed (6mph as this is on the Norfolk
Broads) the stern seems to sit slightly higher in the water (unless I'm
imagining this!). At full throttle the bow rises very noticeably. As for
stability - almost the same (maybe slightly worse) at lower speed - easier
to
hold at high speed but still room for improvement.

So having set the scene the specific questions a

(1) How much ballast should I reasonably install?

(2) To equal the 20 stone person sitting on the front would need
another 120kg (or ANOTHER 5 bags) - is that sensible? Is this a sensible
indication of the stability that can be achieved or am I misguided here?

(3) Given the way the handling of the boat has recently changed am I still
doing the right thing by having ballast in the bow - or should I remove all
of it?

Any advice gratefully received!

Andy

snip
Earlier in the season with three on board, at one point the largest
member of the crew (I'd guess ~20 stone) decided to sit in the roof of the
fore cabin for the return journey. This has a VERY significant impact - I
lined the boat up with
the middle of the river and, with a very slight infrequent adjustment to
the
helm, it stayed on course - very desirable behaviour but never before
witnessed with this boat.
snip

Without being able to offer "old sea dog" help, all I would advise would be
to remove the ballast in the bow if it is easy to get at and start again. I
guess the original thoughts were that the diesel is heavier than the Volvo
resulting in the stern sitting lower. Do you know the difference in weights?

I'm honestly a novice and may get slated for this idea but... although trim
tabs are designed for planing boats, would they also help to give a bit of
lift to the stern rather than filling the bow with ballast and getting the
boat to sit deeper and deeper?

If the worst comes to the worst you could try taking your big friend out
more often!

Good luck,

David