Make, Model ?

[Nick+Sal]

Hi.
Can anyone give me an ID on this little cat.
It's just over 4m. The only plate I can find on the transom is attached.
Thanks for your help.
Cheers, Nick

 

[Bajansailor]

She does look rather nice - have you just bought her?
That ID plate is rather strange, in that it is not in the 'conventional format - I would hazard a guess that she was built in 1984, but I doubt that 957 in number were built - this is more likely to be 7, re the number shown with the 84.
There is a name on the side of the hull by the transom - what does this say?

 

[Nick+Sal]

Hi, thanks for your reply.
Yes, just been bought with a 25hp Merc bigfoot longshaft.
We've been out a couple of times, but she is only getting to 12mph. I was wondering what size engine she is rated to, and expected performance, as well as as the interest.
The name on the side is 'Double M', just a name I think.
I agree with the year built, with the styling.
Cheers
Nick

 

[Bajansailor]

Yes, just been bought with a 25hp Merc bigfoot longshaft.
We've been out a couple of times, but she is only getting to 12mph.

I doubt that she 'needs' a long shaft leg - and that will be a fair bit of extra drag in the water.
And 25 hp is not a lot relatively, for what is probably a fairly 'heavy' (relatively) 4 m. hull, and with a couple of people on board, 12 mph is probably pretty good going. She should be up and planing at this speed?

 

[Rappey]

I've had two 14ft powered cats and a cat dingy. I put a 90hp 2t on the back and was dissapointed to only get 30knts. It felt like it was accelerating then something was dragging as you could feel it lurching. Decided it was the extra 4" of a long shaft causing the drag.
Raised the engine 4" and speed shot up to 45knts.
As a small cat goes faster the outboard needs trimming up more and more to go even faster.
One of my cats was a panther marine racing boat and originally carried a 150hp.
Raise the engine 4" or borrow a short shaft and I'm sure you will go a lot faster

 

[Boathook]

Hi, thanks for your reply.
Yes, just been bought with a 25hp Merc bigfoot longshaft.
We've been out a couple of times, but she is only getting to 12mph. I was wondering what size engine she is rated to, and expected performance, as well as as the interest.
The name on the side is 'Double M', just a name I think.
I agree with the year built, with the styling.
Cheers
Nick

I associate 'bigfoot' engines with displacement boats hence you are only getting 12mph. What is the prop diameter and pitch?
I suspect that you will require another outboard or just accept the maximum speed you have.

 

[Nick+Sal]

I've had two 14ft powered cats and a cat dingy. I put a 90hp 2t on the back and was dissapointed to only get 30knts. It felt like it was accelerating then something was dragging as you could feel it lurching. Decided it was the extra 4" of a long shaft causing the drag.
Raised the engine 4" and speed shot up to 45knts.
As a small cat goes faster the outboard needs trimming up more and more to go even faster.
One of my cats was a panther marine racing boat and originally carried a 150hp.
Raise the engine 4" or borrow a short shaft and I'm sure you will go a lot faster

Hi
Thanks for the info. Did any of them look like this?
She is very stable and good fun for inshore fishing.
I was wondering about the shaft length as the engine sits low in the water. Is there a rule of thumb for measuring the required leg length on a cat?
Did you use a 'bought' engine lifter? If so, what make?
Cheers

 

[Nick+Sal]

I doubt that she 'needs' a long shaft leg - and that will be a fair bit of extra drag in the water.
And 25 hp is not a lot relatively, for what is probably a fairly 'heavy' (relatively) 4 m. hull, and with a couple of people on board, 12 mph is probably pretty good going. She should be up and planing at this speed?

I associate 'bigfoot' engines with displacement boats hence you are only getting 12mph. What is the prop diameter and pitch?
I suspect that you will require another outboard or just accept the maximum speed you have.

Yes, I read that, but was not sure of the shaft length needed. The prop is standard for a bigfoot. I will probably sell that and buy a short 40, or try a lifter.
Thanks, Nick

 

[Rappey]

Did you use a 'bought' engine lifter? If so, what make?
Cheers

Yes, it was called a piece of 4x2 screwed on top of the transom .
Once I established it was at the correct height I built it properly.
Working out the engine height is difficult as if I remember the water between the hulls is higher than under each transom when planing.
Mine already had previous bolt holes so it was just a case of long or short ?
If yours has a clamp on outboard then it's likely to be at the correct height, it's just getting the correct length leg to match.
Power tilt and trim is a must if you want speed.
A 50hp would probably be better for the boat as a 25 will struggle with any weight ?
I found the cat to be far superior to a monohull for this size of vessel. It just glided smoothly over the waves . Was a far more comfortable ride.
Im still looking for pics.
If you intend to keep the boat you need to try somehow running with the outboard 4" higher before you decide whether to "upgrade" the engine or raise the transom and use the engine you have.

 

[Nick+Sal]

Thanks for your advice, I will try and bodge something together for a test without dumping it in the sea
There are boltholes in the transom, so I will get some heavy angle and make a frame....
Cheers

 

[Rappey]

Try and bolt on your test outboard which will mean drilling new holes , but you can always fill them afterwards plus you get a ply core transom sample to see if it still sound.
I've not seen a cat like yours. It could be a great boat !

 

[QBhoy]

I associate 'bigfoot' engines with displacement boats hence you are only getting 12mph. What is the prop diameter and pitch?
I suspect that you will require another outboard or just accept the maximum speed you have.

Generally just the gearbox that’s bigger. Bugger props than normal for the size too. Handy for pushing heavier loads from a standstill. Displacement or planing. They call it a command thrust these days.

 

[Nick+Sal]

Hi.
I know nothing about props, it seems to be a 'black art'
Will a bigger prop create more top speed, or is it the pitch?
Cheers, Nick

 

[Rappey]

A bigger prop or more pitch would result in more speed but then the engine may not have enough power to turn it.

 

[BruceK]

Hi
Thanks for the info. Did any of them look like this?
She is very stable and good fun for inshore fishing.
I was wondering about the shaft length as the engine sits low in the water. Is there a rule of thumb for measuring the required leg length on a cat?
Did you use a 'bought' engine lifter? If so, what make?
Cheers

Your best bet is looking for a suitable jackplate as getting the height right could involve a series of incremental adjustments to get it right.

Hi.
I know nothing about props, it seems to be a 'black art'
Will a bigger prop create more top speed, or is it the pitch?
Cheers, Nick

Generally speaking you want to look at props suitable for your engine and application then smaller diameter and greater pitch for top speed and the reverse for traction and grunt. You must be able to reach full revs without easily exceeding them. After that it's fine tuning. Can be an expensive game of 2 or 3 props before you find the one most suitable.